[Recovery] only send mapping updates to master if needed

The change added in #6762 helps making sure the pending mapping updates are processed on all nodes to prevent moving shards to nodes which are not yet fully aware of the new mapping. However it introduced a racing condition delete_mapping operations, potentially causing a type to be added after it's deletion. This commit solves this by only sending a mapping update if the mapping source has actually changed.

Closes #6772
[Test] Revert temporary fixes for update mapping on recovery issue

This reverts:
"Test: Temporarily change delete/put_mapping to wait for green": commit e408f8f638c2dd97a3ec86c8a9ac940f43ab37a0.
"[TEST] wait for green to update mapping": commit b3641a2ee6eb23318d49f5f04b39149e70c2b65b.