[worker] Move Yarn version from Mise to Corepack

[sjchmiela]

Why

In #3406 EAS workflow building the worker was not updated to Yarn v4. This breaks building worker.

I tried adding defaults.tools.yarn: 4.12.0, but this unfortunately is not the way to use Yarn v4 on EAS as I've learned. The right way is using Corepack.

However, previously we explicitly did not use Corepack, because pnpm --version check the worker does in the beginning of its run was failing because it was run without cwd, so it was running within worker package which was configured with Yarn.

Since we want to use Yarn v4, we need to figure out a way to use Corepack.

How

• Enabled Corepack.
• Set up yarn executable like the one we have in universe.
• Changed pnpm --version to not run inside worker (so it does not error).
• Removed setup-node for specific Node versions in favor of a Mise override.

Test plan

• Corepack + Yarn resolution checks (local):
  • mise exec node@20.19.4 -- bash -lc 'corepack enable; yarn --version' => 4.12.0
  • same check from scripts/ => 4.12.0
• Worker runtime unit test (local):
  • mise exec node@20.19.4 -- bash -lc 'corepack enable; yarn workspace @expo/worker test:unit -- runtimeEnvironment.test.ts'
• GitHub workflow runs:
  • success on Corepack worker workflow update: https://github.com/expo/eas-cli/actions/runs/22133707462
  • latest run for full set of changes: https://github.com/expo/eas-cli/actions/runs/22133932635

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 52.54%. Comparing base (3716542) to head (87967f4).

Files with missing lines	Patch %	Lines
packages/worker/src/external/analytics.ts	11.12%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3412      +/-   ##
==========================================
- Coverage   52.54%   52.54%   -0.00%     
==========================================
  Files         806      806              
  Lines       33610    33615       +5     
  Branches     6985     6985              
==========================================
+ Hits        17657    17658       +1     
- Misses      15871    15875       +4     
  Partials       82       82              

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