Mesh gateway envoy config should have use_remote_address set to true

[wjrbetts]

What happened?

The mesh gateway envoy proxy has the default value of false for use_remote_address in the HTTP connection manager config.

The documentation makes it clear that this should be set to true when the downstream is untrusted:

and

This affects how headers such as x-forwarded-for and x-forwarded-proto are treated.

For example, despite the fact that the connection with the downstream is TLS, our mesh gateway redirects the client because the x-forwarded-proto is (incorrectly) set to http by the client and we have require_tls set to all.