refactor(core): Remove custom event and replay behavior.

[tbondwilkinson]

These behaviors have been moved back to g3.

PR Checklist

Please check if your PR fulfills the following requirements:

• [x] The commit message follows our guidelines: https://github.com/angular/angular/blob/main/CONTRIBUTING.md#commit
• [x] Tests for the changes have been added (for bug fixes / features)
• [x] Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• [ ] Bugfix
• [ ] Feature
• [ ] Code style update (formatting, local variables)
• [x] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] CI related changes
• [ ] Documentation content changes
• [ ] angular.io application / infrastructure changes
• [ ] Other... Please describe:

[tbondwilkinson]

TESTED=TGP

[tbondwilkinson]

Caretaker note:

• Copybara CL required to create sync CL: cl/631196825
• BUILD changes required to patch into sync CL: cl/631207106

[AndrewKushnir]

@tbondwilkinson this PR conflicts with the main branch (a golden file needs an update (likely a revert)) after merging https://github.com/angular/angular/pull/55587. Could you please rebase and remove the "cleanup" label from this PR when you get a chance?

[tbondwilkinson]

@tbondwilkinson this PR conflicts with the main branch (a golden file needs an update (likely a revert)) after merging #55587. Could you please rebase and remove the "cleanup" label from this PR when you get a chance?

Done!

[atscott]

This PR was merged into the repository by commit 76d0aea89b1d34a90761d15829cd0c0ca6b44726.

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