Remove traces of USE_ALLOCATION_SOURCES

[cdosborn]

Description

Remove traces of USE_ALLOCATION_SOURCES. This variable allowed us to transition from the old allocation system to the new one. We no longer use the old one and can remove all the conditional logic.

Checklist before merging Pull Requests

• Add an entry in the changelog
• Reviewed and approved by at least one other contributor.
• New variables supported in Clank
  • Remove unused USE_ALLOCATION_SOURCE(S) variables clank#275

[cdosborn]

@Tharon-C, i'm adding @c-mart since he reviewed the secrets prs, and is already familiar

[c-mart]

I'm not the right person to green-light this one (not familiar enough with Troposphere to understand the code changes), but the aim makes sense given the environment-specific PRs.

[cdosborn]

I forgot that there were more changes than just removing a variable

[Tharon-C]

Built and tested locally, all of the removed branch logic returns the correct way and is formatted.
Thanks @cdosborn! 👍