[native] Fix Timestamp position when focusing RobotextMessage with InlineEngagement

Summary:
We shouldn't include the InlineEngagement in the View that gets measured. By removing this, I fixed a visual glitch where the Timestamp for a robotext message would jump higher on the screen when the robotext was selected.

Depends on D13680

Test Plan:

1. I reacted to a robotext where the timestamp was already showing. Then I pressed it, and made sure there were no visual glitches or logs about incorrect height
2. Same as above, except where the timestamp wasn't showing

Reviewers: tomek

Reviewed By: tomek

Differential Revision: https://phab.comm.dev/D13681