LU-11010 tests: remove calls to return after skip()

LU-11010 tests: remove calls to return after skip()

The skip() routine now contains a call to exit. All calls
to skip() and skip_env() should be reviewed and calls to
return that followed skip() should be removed.

This is the second patch in a series that removes calls
to return after skip() in the Lustre test suites.

Calls to return after skip() are removed for:
dne_sanity
insanity
obdfilter-survey
sgpdd-survey

Test-Parameters: trivial testlist=dne-sanity,insanity,obdfilter-survey,sgpdd-survey
Signed-off-by: James Nunez <james.a.nunez@intel.com>
Change-Id: I4b9aeaeddd673dcba371b8340dd635ddeed2b6be
Reviewed-on: https://review.whamcloud.com/32731
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Wei Liu <sarah@whamcloud.com>
Reviewed-by: Emoly Liu <emoly@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>