mach commands now default to using a temporary application data directory

[Dave Townsend]

Bug 1977540 has landed, which means that mach run and tests will now start Firefox using a custom application data directory. This means that tests cannot make changes to your normal profiles. Additionally, on macOS 27 where access to Firefox's normal data is restricted you don't need to give your terminal additional privileges.

If you want to access your normal profiles with mach run you should use the --default-appdata command line argument.