run root python helpers in isolated mode and keep HOME=/config for non-root containers

The previous commit only set HOME=/config when dropping from root, so a container started with --user lost it. The other root-run helpers in the go2rtc, nginx, and certsync scripts now use python3 -I too, so they never load user site-packages or PYTHON* variables.

docker/main/rootfs/etc/s6-overlay/s6-rc.d/go2rtc/run

@@ -59,7 +59,7 @@ function get_ip_and_port_from_supervisor() {
 
 function set_libva_version() {
     local ffmpeg_path
-    ffmpeg_path=$(python3 /usr/local/ffmpeg/get_ffmpeg_path.py)
+    ffmpeg_path=$(python3 -I /usr/local/ffmpeg/get_ffmpeg_path.py)
     LIBAVFORMAT_VERSION_MAJOR=$("$ffmpeg_path" -version | grep -Po "libavformat\W+\K\d+")
     export LIBAVFORMAT_VERSION_MAJOR
 }
@@ -79,7 +79,7 @@ if [[ ! -f "/dev/shm/go2rtc.yaml" ]]; then
         get_ip_and_port_from_supervisor
     fi
 
-    python3 /usr/local/go2rtc/create_config.py
+    python3 -I /usr/local/go2rtc/create_config.py
 else
     echo "[WARNING] Unable to remove existing go2rtc config. Changes made to your frigate config file may not be recognized. Please remove the /dev/shm/go2rtc.yaml from your docker host manually."
 fi
@@ -87,10 +87,10 @@ fi
 # HomeKit persistence. The helper is symlink-safe; hand off to go2rtc only when dropping.
 readonly homekit_config_path="/config/go2rtc_homekit.yml"
 if [[ "$(id -u)" -eq 0 && "$runs_as_root" -eq 0 ]]; then
-    python3 /usr/local/go2rtc/prepare_homekit.py "${homekit_config_path}" --chown
+    python3 -I /usr/local/go2rtc/prepare_homekit.py "${homekit_config_path}" --chown
     chown -h go2rtc:go2rtc /dev/shm/go2rtc.yaml 2>/dev/null || true
 else
-    python3 /usr/local/go2rtc/prepare_homekit.py "${homekit_config_path}"
+    python3 -I /usr/local/go2rtc/prepare_homekit.py "${homekit_config_path}"
 fi
 
 readonly config_path="/config"