Don't fail on git_pillar tests when destructive tests are not enable
Don't fail on git_pillar tests when destructive tests are not enable

This fixes the following when running `python tests/runtests.py --ext-pillar`:

 --------  Tests with Errors  ------------------------------------------------------------------------------------------------------------------------
   -> tearDownClass (integration.pillar.test_git_pillar.TestGitPythonSSH)  ...........................................................................
       Traceback (most recent call last):
         File ".../salt/tests/support/gitfs.py", line 481, in tearDownClass
           if cls.case.sshd_proc is not None:
       AttributeError: 'NoneType' object has no attribute 'sshd_proc'
   ...................................................................................................................................................
   -> tearDownClass (integration.pillar.test_git_pillar.TestPygit2SSH)  ..............................................................................
       Traceback (most recent call last):
         File ".../salt/tests/support/gitfs.py", line 481, in tearDownClass
           if cls.case.sshd_proc is not None:
       AttributeError: 'NoneType' object has no attribute 'sshd_proc'
   ...................................................................................................................................................
 -----------------------------------------------------------------------------------------------------------------------------------------------------

Signed-off-by: Mathieu Parent <ad270136fc309d4a93a2d2e3357af2b2444ac7c1@gmail.com>
(cherry picked from commit 84e9fce9bb715137474316edb1a2a83f106ba26e)

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt