Revert "[DocsUI M3] Centre items in grid layout"

Revert submission 32486319

Reason for revert: The FrameLayout makes the clickable area of the grid
item far too large. This leads to weird behaviour such as the hover
state appear when the user's cursor is far away from the visible item.

Reverted changes: /q/submissionid:32486319

Change-Id: I6b99b8568ad79f49b3b75feb15d1c95907ea5f80