[BUGFIX] Update nginx deployment to mount nginx.conf as file

[blut]

What this PR does

At the moment, the nginx-config configmap is mounted as folder, masking everything else that is located in /etc/nginx.
I'm trying to load a module in the nginx.conf with load_module modules/ngx_http_js_module.so;.

With the current setup, this fails with the following logs:
/docker-entrypoint.sh: No files found in /docker-entrypoint.d/, skipping configuration 2023/05/09 11:46:27 [emerg] 1#1: dlopen() "/etc/nginx/modules/ngx_http_js_module.so" failed (/etc/nginx/modules/ngx_http_js_module.so: cannot open shared object file: No such file or directory) in /etc/nginx/nginx.conf:1 nginx: [emerg] dlopen() "/etc/nginx/modules/ngx_http_js_module.so" failed (/etc/nginx/modules/ngx_http_js_module.so: cannot open shared object file: No such file or directory) in /etc/nginx/nginx.conf:1

With the proposed change, the nginx.conf file is still mounted to /etc/nginx/nginx.conf, however loading modules is now possible.

Unfortunately, I did not find any parameters to nginx which would allow an alternative module path (e.g. in /usr/lib/nginx/modules) and since the directory is mounted read-only, it is not possible copying the module through an entrypoint script.

Alternative fixes would include larger changes, such as moving the config volume & mount to the values.yaml

Which issue(s) this PR fixes or relates to

Recreates #4954

Checklist

• Tests updated.
• Documentation added.
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX].
• about-versioning.md updated with experimental features.

[CLAassistant]

All committers have signed the CLA.

[dimitarvdimitrov]

awesome, thanks for getting back to this :) LGTM