chore: remove deprecated proxy-ports functions and and plugin subcommands

These were deprecated in 0.31.0 in favor of the ports plugin.

plugins/common/functions

@@ -758,12 +758,6 @@ docker_cleanup() {
   "$PLUGIN_CORE_AVAILABLE_PATH/common/common" --quiet docker-cleanup "$APP"
 }
 
-get_available_port() {
-  declare desc="returns first currently unused port > 1024"
-  dokku_log_warn "Deprecated: please use the 'ports-get-available' plugin trigger instead"
-  plugn trigger ports-get-available
-}
-
 dokku_auth() {
   declare desc="calls user-auth plugin trigger"
   export SSH_USER=${SSH_USER:=$USER}
@@ -827,25 +821,6 @@ get_ipv6_regex() {
   echo "${RE_IPV6}\$"
 }
 
-get_dockerfile_exposed_ports() {
-  declare desc="return all exposed ports from passed file path"
-  dokku_log_warn "Deprecated: this function should not be used in app code"
-
-  local DOCKERFILE_PORTS=$(grep -E "^EXPOSE " "$1" | awk '{ print $2 }' | xargs) || true
-  echo "$DOCKERFILE_PORTS"
-}
-
-get_exposed_ports_from_image() {
-  declare desc="return all exposed ports from passed image name"
-  dokku_log_warn "Deprecated: this function should not be used in app code"
-
-  local IMAGE="$1"
-  verify_image "$IMAGE"
-  # shellcheck disable=SC2016
-  local DOCKER_IMAGE_EXPOSED_PORTS="$("$DOCKER_BIN" image inspect --format '{{range $key, $value := .Config.ExposedPorts}}{{$key}} {{end}}' "$IMAGE")"
-  echo "$DOCKER_IMAGE_EXPOSED_PORTS"
-}
-
 get_entrypoint_from_image() {
   declare desc="return .Config.Entrypoint from passed image name"
   local IMAGE="$1"