Disable drag-drop of files such as images replacing tab for CCT

Support for drag-drop of files was recently added to clank which had
the unintended side effect that dropping a file into a page in a
CCT / TWA which is not registered to handle the drop event will
replace the tab contents with the file (e.g. image).

This fixes clank to set the accept_load_drops param to false for CCT
to match the behavior of PWAs on other platforms.

Bug: 409632787
Change-Id: I4340b11eede64ab0c66ed790ca95db50e3bc70e1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6814772
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Commit-Queue: Joel Hockey <joelhockey@chromium.org>
Reviewed-by: Michael Thiessen <mthiesse@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1498987}