Fix content stripping due to Highlight block raw transform

[AnthonyLedesma]

Description

The raw transforms definition is traced to be the issue causing the stripping of HTML markup from paste contents. It seems that at some point the editor transforms stopped working as expected. Our Jest tests continued to pass however giving us a false sense of validation. The tests continued to pass until I removed the transform definition. That might indicate a change in approach for how Core does raw transforms, our tests for raw transforms likely need updating.

We used a core function to determine which markup to keep. getPhrasingContentSchema
Seemingly at some point, the raw transforms started to diverge from the given schema and instead targeted all pasted content.

Screenshots

Types of changes

Removal of a non-functional raw transform definition.
Disable of raw transform test specifically related to this logic.

How has this been tested?

Tested manually in the editor.

Acceptance criteria

Should be able to post formatted content into the editor.

Checklist:

• My code is tested
• My code follows accessibility standards
• My code has proper inline documentation
• I've included any necessary tests
• I've included developer documentation
• I've added proper labels to this pull request