proxy_request_buffering should be disabled for some paths the nginx controller

On GitLab.com, we disable proxy_request_buffering for certain paths due to disk issues on the git-* fleet related to git https pushes of large files.

More details in gitlab-org/omnibus-gitlab#4010 (closed)

The chart default is to enable proxy_request_buffering which may be appropriate for web and api but not git https, this issues is to discuss whether we should make this a chart default.

As a workaround for GitLab.com, we can disable proxy_request_buffering globally with an annotation:

nginx.ingress.kubernetes.io/proxy-request-buffering: "off"

but this is only temporary, as we add more services.