clean up unused match decision reasons

[dtgreiner]

Merging this PR

• use the squash-merge strategy for PRs targeting a release-X branch
• use a merge-commit or rebase strategy for PRs targeting the stable branch

Description

Remove unreferenced MatchDecisionReasons classes & cleanup unused code in referenced classes.

Type of change

Code clean-up

Checklist before requesting review

• I have performed a self-review of my code
• I have run the code that is being changed under ideal conditions, and it doesn't fail
• I have updated the documentation (or not applicable)
• I have added spec tests (or not applicable)
• I have provided testing instructions in this PR or the related issue (or not applicable)

[eanders]

Thanks @dtgreiner !