Gutenberg: remove Yjs from the core-data package

[ellatrix]

In ​https://github.com/WordPress/wordpress-develop/pull/10355 it was discovered that Yjs is bunded in core-data package by accident, which probably comes from the work on real time collaborative editing (​https://github.com/WordPress/gutenberg/issues?q=state%3Aclosed%20label%3A%22%5BFeature%5D%20Real-time%20Collaboration%22).

This needs to be investigated and removed. In the meantime, I added core-data to the ignore list so that we can the Gutenberg package sync is unblocked: ​https://github.com/WordPress/wordpress-develop/pull/10355.

Cc @czarate

[wildworks]

@ellatrix @czapla, I would like to confirm by when this ticket needs to be resolved for the 6.9 release. Is this issue high-impact? Or can it be punted to 7.0?

Trac ticket: https://core.trac.wordpress.org/ticket/64120

[ellatrix]

In 61184:

Gruntfile: verify:source-maps: restore for core-data.

Yjs was bundled by accident in the core-data package, so we had to ignore the source map verification in an earlier package sync ([61009]). This can now be restored because the issue was fixed in ​https://github.com/WordPress/gutenberg/pull/72503.

Fixes #64120.