Revert "Revert "streaming: Do not invalidate cache if no sstable is added in flush_streaming_mutations""
Revert "Revert "streaming: Do not invalidate cache if no sstable is added in flush_streaming_mutations""

With #4446 fixed, this commit can be reverted.

This reverts commit 454e7e01093345e8376452b1b556a8171a28a4a6.

avikivity/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla