[Filestore] fix node attributes caching invalidation for edge cases

[tindarid]

Original issue: #5293

Relevant comment section: #6203 (comment)

1. For directory chunks loaded from persistent storage we should always invalidate attributes (for more details: check comment section)
2. TBD: on completion of, for example, unlink we now invalidate entry timeouts, but seems like we should invalidate attributes too?