tests: give more room for slowness in test-run-tests.t
The test expected any run-test.py run to end in less than 10 seconds. On slower
loaded CI machine, this gets slower than that. We give a bit more room to the
regexp.
local test passed
addgroupcopy test passed
clone test passed
lowlevelcopy test passed
slicing test passed
issnapshot test passed
findsnapshot test passed