[devtools] qunit: only start firefox once per test The separate profile initialization step doesn't seem necessary anymore. This was due to the system-wide installation of the "Sage" Firefox extensions which breaks -url on a fresh profile. Removing this obnoxious extension allows us to launch Firefox in a standard way. Related to #5533333.

option_group_changed('port', 'main', 'web')
option_group_changed('query-log-file', 'main', 'web')
option_group_changed('profile', 'main', 'web')
option_group_changed('max-post-length', 'main', 'web')