Reverts flutter/flutter#143334

Initiated by: hangyujin

Reason for reverting: broke g3 tests

Original PR Author: hangyujin

Reviewed By: {LongCatIsLooong}

This change reverts the following previous change:
Original Description:
Add a semantics flag to   text field to fix https://github.com/flutter/flutter/issues/143337 (in IOS the disabled text field is not read `dimmed`)

internal: b/322345393