fix(eas-cli): avoid malforming app.json with empty .expo object

[byCedric]

Why

app.json may contain either a root level .expo object with all config options or no .expo property at all. @expo/config reads them both as valid Expo config files.

This removes the unnecessary .expo change, allowing app.json files without .expo property.

Note, this is just one instance but I think there are more invalid instances within eas-cli. Once SDK 52 is out, I'd love to revise the config loading that we use and get fully rid of this limitation.

How

• Removed ensureStaticExpoConfigIsValidAsync as this malforms projects using no .expo property

Test Plan

• $ bun create expo ./test
• Change app.json to drop the root .expo property (use .expo as root)
• $ cd ./test
• $ eas deploy + setup project ID
• $ eas deploy
• Subsequent run should be possible without EAS malforming the app.json file.

[github-actions]

Size Change: +907 B (0%)

Total Size: 52.9 MB

Filename	Size	Change
./packages/eas-cli/dist/eas-linux-x64.tar.gz	52.9 MB	+907 B (0%)

_{compressed-size-action}

[github-actions]

✅ Thank you for adding the changelog entry!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 52.09%. Comparing base (d33ebe1) to head (d856400).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2573      +/-   ##
==========================================
- Coverage   52.12%   52.09%   -0.03%     
==========================================
  Files         559      559              
  Lines       21111    21101      -10     
  Branches     4317     4315       -2     
==========================================
- Hits        11003    10991      -12     
- Misses       9230     9232       +2     
  Partials      878      878              

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