p13n: prevent text overflow

When the text input is already at the max length, clicking on a
suggestion button allowed users to overflow the max length. The search
result is always blocked due to the text length.

Do not add the suggestion to the end of the text if it puts the user
over the max length of the text input.
https://screencast.googleplex.com/cast/NDg3ODQ5ODk0NTU2NDY3MnxiMjA1YmIxMC01Yw

BUG=b:360203915
TEST=browser_tests *SeaPenInputQuery*

Change-Id: I51313348e1f445fabe685cf070182c3fdba96fff
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5792136
Reviewed-by: Jason Thai <jasontt@chromium.org>
Commit-Queue: Erica Lee <ericamlee@google.com>
Cr-Commit-Position: refs/heads/main@{#1342912}