Recovery: mapping check during phase2 should be done in cluster state update task

Before phase2 we check verify that the local mapping is in sync with the cluster state mapping (and send & wait on a master update mapping task if not). This check should be done under a cluster state update task to make sure an incoming cluster state update to do not change things while we check.

Closes #7744
Tests: extend testRecoverFromPreviousVersion to sometimes index during relocation

Relates to #7729

Closes #7768