gbproxy: Reduce timeout to fix flaky test

The individual timeouts in TC_BVC_bringup_conflicting add up to almost
15.0s (the Tguard timeout) which causes the test to sometimes fail.
Decrease the time waiting for all BVCs to be unblocked from 10s to 5s,
in reality this should be plenty time.

Change-Id: I620ce90f9e6b54cc94b4d36ac123f43d8d809f47
1 file changed