Undo a rearchitecture that breaks us downstream

[HeyImChris]

Please select one of the following

• I am removing an existing difference between facebook/react-native and microsoft/react-native-macos 👍
• I am cherry-picking a change from Facebook's react-native into microsoft/react-native-macos 👍
• I am making a fix / change for the macOS implementation of react-native
• I am making a change required for Microsoft usage of react-native

Summary

This change I'm reverting for the 63 stable branch is an improvement in that we only do the global JS variable init once, but it has the downside that it splits out the JS runtime init from the bundle loading which breaks a scenario we rely on downstream.

I'm still investigating how to rearchitect our downstream client code to be compatible with this change which is why I'm just making this revert in 0.63 instead of master. In the short term, we need to unblock ourselves and anyone else that isn't set up to properly handle this new scenario of rearchitecting the SDX setup.

I also hit some failures using Flipper. We need a different version than is compatible so for now I disabled Flipper as we don't need it on.

git revert 6f627f684bb6506a677c9632b2710e4a541690a9

Changelog

[General] [Minor] - git revert a 63 initialization rearchitecture

Test Plan

This is going back to what is in 0.62 so it should all still work as well as 0.62 did. I ran the test app and basic scenarios seem to still work as expected.

[pull-bot]

	Warnings
⚠️	❔ Base Branch - The base branch for this PR is something other than master. Are you sure you want to merge these changes into a stable release? If you are interested in backporting updates to an older release, the suggested approach is to land those changes on master first and then cherry-pick the commits into the branch for that release. The Releases Guide has more information.

Messages

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📋 Verify Changelog Format - A changelog entry has the following format: [CATEGORY] [TYPE] - Message. Details CATEGORY may be: General macOS iOS Android JavaScript Internal (for changes that do not need to be called out in the release notes) TYPE may be: Added, for new features. Changed, for changes in existing functionality. Deprecated, for soon-to-be removed features. Removed, for now removed features. Fixed, for any bug fixes. Security, in case of vulnerabilities. MESSAGE may answer "what and why" on a feature level. Use this to briefly tell React Native users about notable changes.

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