Fix; declare DOMAIN variable for docker setup (#10780)

In the /install form, the value for SSH Server Domain is taken form the DOMAIN variable
and overwrites SSH_DOMAIN environment variable set the first time if nothing done

Co-authored-by: Adrian POIGET <adrian.poiget@viveris.fr>

docker/root/etc/s6/gitea/setup

@@ -26,6 +26,7 @@ if [ ! -f ${GITEA_CUSTOM}/conf/app.ini ]; then
     # Substitude the environment variables in the template
     APP_NAME=${APP_NAME:-"Gitea: Git with a cup of tea"} \
     RUN_MODE=${RUN_MODE:-"dev"} \
+    DOMAIN=${DOMAIN:-"localhost"} \
     SSH_DOMAIN=${SSH_DOMAIN:-"localhost"} \
     HTTP_PORT=${HTTP_PORT:-"3000"} \
     ROOT_URL=${ROOT_URL:-""} \

docker/root/etc/templates/app.ini

@@ -12,6 +12,7 @@ TEMP_PATH = /data/gitea/uploads
 
 [server]
 APP_DATA_PATH = /data/gitea
+DOMAIN           = $DOMAIN
 SSH_DOMAIN       = $SSH_DOMAIN
 HTTP_PORT        = $HTTP_PORT
 ROOT_URL         = $ROOT_URL