fix(workflow): Replace getSantry with dedicated GH app for api schema workflow

[Jeffreyhung]

We added the new default rulesets that requires all commit to go through PRs and that breaks this workflow.
Added the following changes to fix it

• created a new dedicated github app for this
• added the github app to allowlist in the ruleset
• update the workflow to use the new github app instead of getSantry
• added the app-id and private key through org secrets and variables
• replaced getsentry/action-github-app-token with actions/create-github-app-token so that we have options to control the repo scope of the short-live token
• update the git commit info to use the github app

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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