fix: metacache should only rename entries during cleanup (#11503)

To avoid large delays in metacache cleanup, use rename
instead of recursive delete calls, renames are cheaper
move the content to minioMetaTmpBucket and then cleanup
this folder once in 24hrs instead.

If the new cache can replace an existing one, we should
let it replace since that is currently being saved anyways,
this avoids pile up of 1000's of metacache entires for
same listing calls that are not necessary to be stored
on disk.

cmd/storage-datatypes.go

@@ -85,18 +85,18 @@ type FileInfoVersions struct {
 	Versions []FileInfo
 }
 
-// forwardPastVersion will truncate the result to only contain versions after 'v'.
-// If v is empty or the version isn't found no changes will be made.
-func (f *FileInfoVersions) forwardPastVersion(v string) {
-	if v == "" {
-		return
+// findVersionIndex will return the version index where the version
+// was found. Returns -1 if not found.
+func (f *FileInfoVersions) findVersionIndex(v string) int {
+	if f == nil || v == "" {
+		return -1
 	}
 	for i, ver := range f.Versions {
 		if ver.VersionID == v {
-			f.Versions = f.Versions[i+1:]
-			return
+			return i
 		}
 	}
+	return -1
 }
 
 // FileInfo - represents file stat information.