[CLD-7062] Push proxy chart revisit ingress spec

[phoinixgrr]

Summary

This covers the case when special ingress spec is needed to manage different http paths. For example, provides support for the following configuration:

          - backend:
              service:
                name: response-403
                port:
                  name: use-annotation
            path: /metrics
            pathType: Prefix

In which along with the following Ingress annotation and the use of AWS ALB Controller:

    alb.ingress.kubernetes.io/actions.response-403: >
          {"type":"fixed-response","fixedResponseConfig":{"contentType":"text/plain","statusCode":"403","messageBody":"403 Not Allowed"}}

Will result in different handling of specific paths

The template continues to render as usual in case customService directive is not in use.

Ticket Link

Ticket: https://mattermost.atlassian.net/browse/CLD-7062