Fixed DEVSTACK_GATE_TEMPEST_REGEX.

This string was incorrectly tested with an integer comparison
operator (-ne) instead of a string comparison operator (!=).

Change-Id: I4ba8da1940c882a40c81ff38d80e0750e21d3daf
Closes-Bug: #1292138
Merge "Fixed DEVSTACK_GATE_TEMPEST_REGEX."