removes mv2 builds; simplifies workflows

[grahamlangford]

What does this PR do?

• Eliminates mv2 builds in CI

Discussion

• Originally considered just changing the ci.yml to upload mv3 to Rainforest instead of mv2
• And eliminate the Playwright runs for mv2
• Decided there's really no reason to keep mv2 builds around

Future Work

• Fix Rainforest tests that rely on the sidebar
• Simplify manifest.json and manifest.mjs (can hardcode mv3 concerns)

Checklist

• Designate a primary reviewer @BLoe

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.44%. Comparing base (6d95047) to head (c55793a).
Report is 78 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8482      +/-   ##
==========================================
- Coverage   73.47%   73.44%   -0.04%     
==========================================
  Files        1334     1352      +18     
  Lines       41259    41563     +304     
  Branches     7686     7799     +113     
==========================================
+ Hits        30316    30524     +208     
- Misses      10943    11039      +96     

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[github-actions]

Playwright test results

 55 passed
 1 flaky

Details

 Open report ↗︎
 56 tests across 19 suites
 15 minutes, 51 seconds
 c55793a

Flaky tests

edge › tests/regressions/doNotCloseSidebarOnPageEditorSave.spec.ts › #8104: Do not automatically close the sidebar when saving in the Page Editor

[github-actions]

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