LU-3665 tests: Cleanup echo client after obdfilter-survey

LU-3665 tests: Cleanup echo client after obdfilter-survey

Some failures of obdfilter-survey do not cause an error in
obdfilter-survey.sh In some cases obdfilter-survey did not
cleanup echo clients it had created and that could hang
umount of osts.
Change test-framework.sh::cleanupall to remove echo clients before
trying to umount to prevent the echo clients from holding the OST or
MDS/MGS open forever.

Test-Parameters: trivial testlist=obdfilter-survey osscount=1 ostcount=2 mdscount=1 mdtcount=1
Test-Parameters: trivial testlist=obdfilter-survey mdtfilesystemtype=zfs ostfilesystemtype=zfs osscount=1 ostcount=2 mdscount=1 mdtcount=1
Signed-off-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Change-Id: I63ae59da84101c782aa9d5e7216cce3b3b1ff2fe
Reviewed-on: https://review.whamcloud.com/9350
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: Andriy Skulysh <c17819@cray.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>