LU-10255 tests: Fix wrong comparison operator in sanity 129

LU-10255 tests: Fix wrong comparison operator in sanity 129

Currently sanity 129 uses numerica (-eq) operator to check whether
the has_warning variable is true or false depending on whether
expected warnings have been detected. This is wrong since bash
doesn't really have bolean types and true/false are not evaluated to
1/0. This results in the following bash error when the test is run:

    ./sanity.sh: line 9244: [: true: integer expression expected

Fix it by using the correct string operator '=' to check for
correct value.

Test-Paramters: clientdistro=sles12sp2 testlist=sanity
Test-Paramters: clientdistro=sles12sp3 testlist=sanity

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Change-Id: I071dcb3001ea9b2e5806d346dcd48bfcaf3297e9
Reviewed-on: https://review.whamcloud.com/30149
Reviewed-by: James Nunez <james.a.nunez@intel.com>
Tested-by: Jenkins
Reviewed-by: Saurabh Tandan <saurabh.tandan@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>