Following  SERVER-90202 and SERVER-91397, all github PRs have the following default description. Ideally, we would have some information that asks the PR author to specify their test plan (but without including this information in the commit description that gets added to our git history). As such, this ticket proposes the following:

• Keep the current message as is, but have it specify that the user must include a comment describing the test plan before merging.
• Then, to prevent this information from being committed, we can have commit message validation block merge if there is no comment containing a test plan on the PR. 

The advantage of the above is that we ensure that test plans don't get included in the commit message.

Another idea is that we can have the template specify a test plan template, but:

• Explicitly state that this must be removed from the commit message prior to merging.
• Adding validation which enforces this (by doing something like checking for evergreen links, the header of original template, or something else).