fix: revert allow offline disks on fresh start (#19052)

the PR in #16541 was incorrect and hand wrong assumptions
about the overall setup, revert this since this expectation
to have offline servers is wrong and we can end up with a
bigger chicken and egg problem.

This reverts commit 5996c8c4d5.

Bonus:

- preserve disk in globalLocalDrives properly upon connectDisks()
- do not return 'nil' from newXLStorage(), getting it ready for
  the next set of changes for 'format.json' loading.

cmd/format-erasure.go

@@ -306,7 +306,12 @@ func countErrs(errs []error, err error) int {
 	return i
 }
 
-// Check if unformatted disks are equal to write quorum.
+// Does all errors indicate we need to initialize all disks?.
+func shouldInitErasureDisks(errs []error) bool {
+	return countErrs(errs, errUnformattedDisk) == len(errs)
+}
+
+// Check if unformatted disks are equal to 50%+1 of all the drives.
 func quorumUnformattedDisks(errs []error) bool {
 	return countErrs(errs, errUnformattedDisk) >= (len(errs)/2)+1
 }
@@ -773,9 +778,6 @@ func initFormatErasure(ctx context.Context, storageDisks []StorageAPI, setCount,
 		hostCount := make(map[string]int, setDriveCount)
 		for j := 0; j < setDriveCount; j++ {
 			disk := storageDisks[i*setDriveCount+j]
-			if disk == nil {
-				continue
-			}
 			newFormat := format.Clone()
 			newFormat.Erasure.This = format.Erasure.Sets[i][j]
 			if deploymentID != "" {
@@ -800,14 +802,8 @@ func initFormatErasure(ctx context.Context, storageDisks []StorageAPI, setCount,
 						logger.Info("   - Drive: %s", disk.String())
 					}
 				})
-				var warning string
-				if wantAtMost == 0 {
-					warning = fmt.Sprintf("Host %v has all drives of set. ", host)
-				} else {
-					warning = fmt.Sprintf("Host %v has more than %v drives of set. ", host, wantAtMost)
-				}
-				logger.Info(color.Yellow("WARNING: ") + warning +
-					"A host failure will result in data becoming unavailable.")
+				logger.Info(color.Yellow("WARNING:")+" Host %v has more than %v drives of set. "+
+					"A host failure will result in data becoming unavailable.", host, wantAtMost)
 			}
 		}
 	}