
Fixes https://github.com/flutter/flutter/issues/156456
There is a known long running test that has been bumping up against the default timeout. This adjusts the perTestTimeout for the devicelab tests to add 15 seconds to stop this from flaking.
The test is question: 82ebb74c64/dev/devicelab/test/run_test.dart (L76)
`test/run_test.dart: run.dart script prints a message after a few seconds when failing to connect (this test takes >10s)`