Split up and organize the Bitbucket test suite.
Review Request #9786 — Created March 15, 2018 and submitted — Latest diff uploaded
The Bitbucket tests were mixing service tests and webhook tests, and had
a handful of tests that weren't in the most logical order. This change
splits out the webhook tests into its own suite, and fixes up some
test ordering to help see related tests at a glance.
Unit tests pass.