chore: move catch-all rule to top of CODEOWNERS

[overbalance]

Summary

• Moves the catch-all * @open-telemetry/javascript-approvers rule from the bottom to the top of CODEOWNERS
• CODEOWNERS rules are matched top-to-bottom with later rules taking precedence, so the catch-all must be first for specific rules to properly override it

Test plan

• Verify that PRs touching .github/ files require javascript-maintainers approval
• Verify that PRs touching browser packages require browser-maintainers approval

Verification

Observe that this PR modifies .github/ but only @open-telemetry/javascript-approvers are tagged for review.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.39%. Comparing base (5e6504d) to head (16d91e3).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6297   +/-   ##
=======================================
  Coverage   95.39%   95.39%           
=======================================
  Files         316      316           
  Lines        9574     9574           
  Branches     2216     2216           
=======================================
  Hits         9133     9133           
  Misses        441      441           

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