Fix redirects that were missed in previous sprints

[bmathesonFEC]

Summary

What we're after:
We need to redirect pages that were identified in the RADFAQ review and a previous transition inventory #4512. Several redirects were missed in (#4628, #4619)

New tab created in the 2021 Redirects sheet titled 15.3 redirects and it lists all URLs that were tested in 15.2 and the redirect was not in place.

Completion criteria

• Redirects are merged into the release (See spreadsheet for redirects)
• 2021 spreadsheet is updated
• Testing ticket is created to be done in the next sprint after deploy of releases to test redirects and implement any needed www ones.
• Take down ticket is created to take down the redirected items.

[bmathesonFEC]

Redirects added as a commit to Kathy's FEC-Proxy PR #276