Migrate nightly from scheduled workflow to scheduled pipeline (#35977)

Summary:
I'm moving nightlies from scheduled workflow to scheduled pipeline.
We're not able to manually retrigger nightlies as they're a scheduled workflow and don't expose a parameter. Here I'm cleaning it up.

Plus I'm:
1. Removing the `main_only` reference which is unused
2. Setting up the `run_release_workflow` and `run_nightly_workflow` parameters.

## Changelog

[INTERNAL] - Migrate nightly from scheduled workflow to scheduled pipeline

Pull Request resolved: https://github.com/facebook/react-native/pull/35977

Test Plan: Will wait for CI results.

Reviewed By: cipolleschi

Differential Revision: D42776969

Pulled By: cortinico

fbshipit-source-id: d4ef9654d23cb91f85ce2b38e75e27dc0c575e95