Enable HTTPS-Only Mode by default in Tor Browser Android

Now that HTTPS-Only Mode is enabled by default in Tor Browser Desktop (#19850 (closed)), it would be good to enable it by default in Tor Browser Android as well, to protect users against SSL strip attacks by hostile exit nodes. Note the feature is already enabled by default in Firefox Focus Android and Mull Browser Android (see https://privacytests.org/android.html), so I expect it should be fairly straightforward to enable this setting.