RTC: Template entities not synced when the editor is in template-locked mode

[mmtr]

Description

When the post editor displays the full site template, the content outside of the post content is not synced over RTC.

Step-by-step reproduction instructions

• Go to Options -> Writing and enable RTC
• Edit the same post with 2 users and enable the template-locked mode:

• Make some changes to the template entities
• Observe how changes are not synced across both users

Screenshots, screen recording, code snippet

Screen.Recording.2026-04-08.at.13.08.23.2.mov

Environment info

• WordPres 6.9.4
• Gutenberg 22.9.0-rc.1

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes

Please confirm which theme type you used for testing.

• Block
• Classic
• Hybrid (e.g. classic with theme.json)
• Not sure

[mmtr]

I think this is actually a duplicate of #76784