Remove XUL layout hacks from base browser

In relation to #41812 (closed), we want to remove some known XUL layout hacks that are no longer needed in base browser.

added 13.0 stable Doing labels

assigned to @henry

marked this issue as related to #41812 (closed)

mentioned in merge request !746 (merged)

marked this issue as related to tor-browser-build#40927 (closed)

marked this issue as related to tor-browser-build#40928 (closed)

closed

added Desktop label

marked this issue as related to tor-browser-build#40965 (closed)

marked this issue as related to tor-browser-build#40966 (closed)