[PinnedTabs] Fix restrained tab grid recycler view

Tab was becoming invisible and goes behind empty area when dragging due
to constrained recycler view area. Wrapped around FrameLayout and maxed
out the length. Directly applying this to recycler view doesn't work
somehow.

This made the pane layout file more predictable too.

After fix video: http://screencast/cast/NjExNzA3Nzk4NjMxMjE5MnwzMDllNTk5MC0yYQ

Bug: 444371602
Change-Id: I3dec8d6e6515ce776b8df9f8295f9bd0923435b1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6937852
Auto-Submit: Madhav Pruthi <madhavpruthi@google.com>
Commit-Queue: Sky Malice <skym@chromium.org>
Reviewed-by: Sky Malice <skym@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1515072}