adhere proxy

[joshhighet]

EXTERNAL_PROXY_HOST destination should be assumed Arti once joshhighet/torsocc#1 is done

isolator/src/launch-browser.sh

Lines 15 to 16 in db1a92a

	/home/toruser/tor-browser/Browser/start-tor-browser \
	--new-window "$BROWSER_URL" ${REMOTE_DEBUG_FLAG:+$REMOTE_DEBUG_FLAG} &

currently ext proxy gets defined through userjs overrides;

isolator/src/entrypoint.sh

Lines 92 to 99 in db1a92a

	PROXY_CONFIG=$(cat <<EOF
	user_pref("network.proxy.type", 1);
	user_pref("network.proxy.socks", "$EXTERNAL_PROXY_HOST");
	user_pref("network.proxy.socks_port", $EXTERNAL_PROXY_PORT);
	user_pref("network.proxy.socks_remote_dns", true);
	user_pref("extensions.torlauncher.start_tor", false);
	user_pref("extensions.torbutton.use_nontor_proxy", true);
	EOF

simplify approach to use TOR_SOCKS_HOST & TOR_SOCKS_PORT with start-tor-browser launcher - ref TorLauncherUtil.sys.mjs