Delete stale branches

[r-bartlett-gsa]

As a DevSecOps specialist, in order to keep our repo clean, I would like to delete old stale branches.

Acceptance criteria:

• [x] Review and delete branches that (below criteria is negotiable):
  • [x] are more than 100 commits behind production
  • [x] haven't been updated in 6 months
  • [x] have already been merged