Allow envBranch to be passed in on CI

[aswamy]

WHY are these changes introduced?

Part of #2267

WHAT is this pull request doing?

• We currently don't parse envBranch and env flags on npx shopify hydrogen deploy command in CI environments
  • Assumption: the original intention was that CI environments would ALWAYS just pick up the branch it is on
  • If you pass in an envBranch that doesn't exist in CI, we push the deploy to preview (as before)

Future task

• env flag will require more effort as it needs to be available on our dependant services
• the current fix only patches it for the envBranch flag

HOW to test your changes?

• Create a hydrogen repo
  • create a branch "fake-branch" and check it out
• Clone this repo and checkout the branch. Run the following
  • npm ci
  • npm run build
  • CI=1 npx shopify hydrogen deploy --env-branch=main --token=<token> --force

Expected:

• On Admin, the deployment should be created under the "Production" environment since you specified the main branch

Post-merge steps

Checklist

• I've read the Contributing Guidelines
• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've added a changeset if this PR contains user-facing or noteworthy changes
• I've added tests to cover my changes
• I've added or updated the documentation

[shopify]

Oxygen deployed a preview of your allow-env-branch-on-ci branch. Details:

Storefront	Status	Preview link	Deployment details	Last update (UTC)
third-party-queries-caching	✅ Successful (Logs)	Preview deployment	Inspect deployment	July 2, 2024 6:58 PM
Skeleton (skeleton.hydrogen.shop)	✅ Successful (Logs)	Preview deployment	Inspect deployment	July 2, 2024 6:58 PM
metaobjects	✅ Successful (Logs)	Preview deployment	Inspect deployment	July 2, 2024 6:58 PM
optimistic-cart-ui	✅ Successful (Logs)	Preview deployment	Inspect deployment	July 2, 2024 6:58 PM
classic-remix	✅ Successful (Logs)	Preview deployment	Inspect deployment	July 2, 2024 6:58 PM
custom-cart-method	✅ Successful (Logs)	Preview deployment	Inspect deployment	July 2, 2024 6:58 PM

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