Fix staging workflow

[hsubox76]

I actually tested this during development by calling the REST endpoint on this branch after each change, so it should all be working now.

• E2E test uses latest Firebase CLI which just recently stopped supporting Node 12
• Update release script so that if it is staging, and in CI, it will publish using the publishInCI() function, which runs the npm publish command on each package one by one, which lets us provide each package's specific wombat-dressing-room token. The simpler publish() function uses changeset publish which is more convenient but doesn't allow us to use wombat-dressing-room.
• Delete release.yml. This used to be triggered on push to the release branch. It's redundant now as the same step is part of the release-staging.yml workflow.

TODO: Production publish script will have to find another way to grab the names of all the packages to publish since it doesn't run bumpVersionForStaging.

[changeset-bot]

⚠️ No Changeset found

Latest commit: bec2a8c

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[google-oss-bot]

Size Report ¹

Affected Products

No changes between base commit (4559c51) and merge commit (dc5644b).

Test Logs

• Base (4559c51): https://github.com/firebase/firebase-js-sdk/actions/runs/2379987769
• Merge (dc5644b): https://github.com/firebase/firebase-js-sdk/actions/runs/2385932779

1. https://storage.googleapis.com/firebase-sdk-metric-reports/ieuZsj1hba.html

[google-oss-bot]

Size Analysis Report ¹

Affected Products

No changes between base commit (4559c51) and merge commit (dc5644b).

Test Logs

• Base (4559c51): https://github.com/firebase/firebase-js-sdk/actions/runs/2379987769
• Merge (dc5644b): https://github.com/firebase/firebase-js-sdk/actions/runs/2385932779

1. https://storage.googleapis.com/firebase-sdk-metric-reports/Hb6c6XF2O3.html

[dwyfrequency]

LGTM