Distributed Learning Technologies

RFC - Update PS-BB integration script

Update the ps-bb integration script on bbutilprd from version 2.5.0 to 2.5.1, including the following changes:

### Added
- REST client uses HTTP connection cache

### Changed
- Course end dates are now omitted by default
- Automatically skips xlist if we are skipping snapshot
- REST client logs in earlier in program flow, should catch certain problems sooner

### Fixed
- Fixed an issue where load date calculation could miss a term
- Fixed an issue where prep area creation was inadvertently skipped

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The most important changes are the prep area and term date bug fixes. The other items will help avoid some pain points that we've encountered over the past year, and finally we will enable HTTP connection caching, which should dramatically improve performance of the API client.

It's particularly important that we deploy the prep area bug fix before faculty start checking in on their Fall courses.

Exact timing for deployment will depend on when the 5:30 AM snapshot finishes running; in recent weeks that has been shortly after 7:00 AM in most cases, so I feel comfortable getting this up and running by the proposed end time of 8:00 AM. Actual deployment should take just a few seconds to pull from GitHub.