Revert "Modifying screenshot button visibility"

This reverts commit 02fc23c9.

Google never added code to change the visibility of the screenshot
button in AOSP, so it gets stuck on GONE. Simply revert the change to
fix it.

Signed-off-by: Danny Lin <danny@kdrag0n.dev>
Change-Id: I5b2558ec2daeff2fd45a64c9ef26b3a8912a2ce7