chore: drop the unpublished upstream delivery and branding residue

The tree still carried a complete second publishing pipeline inherited from
upstream that pgsty has never operated, plus MinIO-branded artwork the fork has
no right to redistribute. None of it is a pgsty release artifact, so the
history-is-immutable rule does not protect it: nothing here was ever published
under this repository's name, and git history plus the pre-cutover tag keep the
provenance.

Removed, by category:

- charts.min.io machinery: CNAME (charts.min.io), _config.yml, index.yaml,
  helm-reindex.sh and 90 helm-releases/minio-*.tgz. GitHub Pages is not enabled
  on this repository, so this was dormant - but enabling Pages for any reason
  would have stood up a convincing impostor of the official MinIO chart
  repository from our own domain.

- Dockerfiles that consume upstream binaries: Dockerfile, Dockerfile.cicd,
  Dockerfile.hotfix, Dockerfile.release, Dockerfile.release.old_cpu,
  Dockerfile.scratch and docker-buildx.sh. These fetch or expect a MinIO-built
  binary; a Silo image must only ever contain an artifact this repository built
  from this commit. Dockerfile.goreleaser, the one the release workflow
  actually uses, stays.

- buildscripts/upgrade-tests/ (compose.yml, minio.env, nginx.conf), which
  pinned minio/minio images through a MINIO_VERSION compose variable. The
  upgrade test is rebuilt on image digests in a later commit.

- docs/hotfixes.md, describing an upstream hotfix distribution channel that
  does not exist for this fork.

- MinIO trademark artwork: .github/logo.svg (a recoloured MinIO wordmark), the
  docs/screenshots/ set, the Grafana dashboard screenshots and
  docs/federation/lookup/bucket-lookup.png. The dashboards themselves are kept
  and rebranded separately; only the images carrying MinIO chrome go.

Deliberately not touched: published releases, tags, image digests and package
signatures remain byte-identical. This commit only removes paths that were
never part of a pgsty release.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

buildscripts/upgrade-tests/compose.yml

@@ -1,74 +0,0 @@
-# Settings and configurations that are common for all containers
-x-minio-common: &minio-common
-  image: minio/minio:${MINIO_VERSION}
-  command: server http://minio{1...4}/data{1...3}
-  env_file:
-    - ./minio.env
-  expose:
-    - "9000"
-    - "9001"
-
-# starts 4 docker containers running minio server instances.
-# using nginx reverse proxy, load balancing, you can access
-# it through port 9000.
-services:
-  minio1:
-    <<: *minio-common
-    hostname: minio1
-    volumes:
-      - data1-1:/data1
-      - data1-2:/data2
-      - data1-3:/data3
-
-  minio2:
-    <<: *minio-common
-    hostname: minio2
-    volumes:
-      - data2-1:/data1
-      - data2-2:/data2
-      - data2-3:/data3
-
-  minio3:
-    <<: *minio-common
-    hostname: minio3
-    volumes:
-      - data3-1:/data1
-      - data3-2:/data2
-      - data3-3:/data3
-
-  minio4:
-    <<: *minio-common
-    hostname: minio4
-    volumes:
-      - data4-1:/data1
-      - data4-2:/data2
-      - data4-3:/data3
-
-  nginx:
-    image: nginx:1.19.2-alpine
-    volumes:
-      - ./nginx.conf:/etc/nginx/nginx.conf:ro
-    ports:
-    - "9000:9000"
-    - "9001:9001"
-    depends_on:
-      - minio1
-      - minio2
-      - minio3
-      - minio4
-
-## By default this config uses default local driver,
-## For custom volumes replace with volume driver configuration.
-volumes:
-  data1-1:
-  data1-2:
-  data1-3:
-  data2-1:
-  data2-2:
-  data2-3:
-  data3-1:
-  data3-2:
-  data3-3:
-  data4-1:
-  data4-2:
-  data4-3:

buildscripts/upgrade-tests/minio.env

@@ -1,3 +0,0 @@
-MINIO_ACCESS_KEY=minioadmin
-MINIO_SECRET_KEY=minioadmin
-MINIO_BROWSER=off

buildscripts/upgrade-tests/nginx.conf

@@ -1,68 +0,0 @@
-user  nginx;
-worker_processes  auto;
-
-error_log  /var/log/nginx/error.log warn;
-pid        /var/run/nginx.pid;
-
-
-events {
-    worker_connections  1024;
-}
-
-
-http {
-    include       /etc/nginx/mime.types;
-    default_type  application/octet-stream;
-
-    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
-                      '$status $body_bytes_sent "$http_referer" '
-                      '"$http_user_agent" "$http_x_forwarded_for"';
-
-    access_log  /var/log/nginx/access.log  main;
-
-    sendfile        on;
-    #tcp_nopush     on;
-
-    keepalive_timeout  65;
-
-    #gzip  on;
-
-    # include /etc/nginx/conf.d/*.conf;
-
-    upstream minio {
-        server minio1:9000;
-        server minio2:9000;
-        server minio3:9000;
-        server minio4:9000;
-    }
-
-    # main minio
-    server {
-        listen       9000;
-        listen  [::]:9000;
-        server_name  localhost;
-
-         # To allow special characters in headers
-         ignore_invalid_headers off;
-         # Allow any size file to be uploaded.
-         # Set to a value such as 1000m; to restrict file size to a specific value
-         client_max_body_size 0;
-         # To disable buffering
-         proxy_buffering off;
-
-        location / {
-            proxy_set_header Host $http_host;
-            proxy_set_header X-Real-IP $remote_addr;
-            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
-            proxy_set_header X-Forwarded-Proto $scheme;
-
-            proxy_connect_timeout 300;
-            # Default is HTTP/1, keepalive is only enabled in HTTP/1.1
-            proxy_http_version 1.1;
-            proxy_set_header Connection "";
-            chunked_transfer_encoding off;
-
-            proxy_pass http://minio;
-        }
-    }
-}