Merge PR #36823 into master

* refs/pull/36823/head:
	qa : add a test for the cmd, dump cache
	mds : add timeout to the command, dump cache, to prevent it from running too long and affecting the service

Reviewed-by: Patrick Donnelly <pdonnell@redhat.com>

diff --cc src/mds/MDCache.cc
Simple merge

diff --cc src/mds/MDSDaemon.cc
Simple merge

diff --cc src/mds/MDSRank.cc
Simple merge