Add IPv6 support to default.conf.template for OSS/Plus images

The OSS and Plus base images were missing IPv6 support.
The nginx base image's IPv6 enabler script modifies /etc/nginx/conf.d/default.conf,
but the template processing (which runs after) overwrites this file,
removing the IPv6 listen directive.

This fix adds both IPv4 and IPv6 listen directives directly to the
source template, ensuring they are present in the final configuration
for OSS and Plus image variants.

Fixes #453

Signed-off-by: Jesse Awan <jesse.awan@sap.com>

Author: I501307

common/etc/nginx/templates/default.conf.template

@@ -32,6 +32,8 @@ js_set $awsSessionToken awscredentials.sessionToken;
 js_set $s3uri s3gateway.s3uri;
 
 server {
+    listen       80;
+    listen       [::]:80;
     include /etc/nginx/conf.d/gateway/server_variables.conf;
 
     # Don't display the NGINX version number because we don't want to reveal