heal: Fix healing empty directories (#7154)
heal: Fix healing empty directories (#7154)

This commit fixes the computation of Before/After healing state
for empty directories.

Issues before the commit:
- Before state doesn't reflect the real status (no StatVol() called)
- For any MakeVol() error, healObjectDir is exited directly, which is
  wrong.

krishnasrinivas/minio,fwessels/minio,krishnasrinivas/minio,minio/minio,aead/minio,aead/minio,krisis/minio,jimjag/minio,donatello/minio,harshavardhana/minio,NitishT/minio,fwessels/minio,fwessels/minio,aead/minio,jimjag/minio,aead/minio,harshavardhana/minio,krisis/minio,balamurugana/minio,donatello/minio,harshavardhana/minio,aead/minio,vadmeste/minio,aead/minio,minio/minio,aead/minio,krishnasrinivas/minio,harshavardhana/minio,harshavardhana/minio,jimjag/minio,aead/minio,fwessels/minio,harshavardhana/minio,harshavardhana/minio,NitishT/minio,balamurugana/minio,harshavardhana/minio,jimjag/minio,vadmeste/minio,NitishT/minio,NitishT/minio,krishnasrinivas/minio