chore(proxy): pre-load native tls certificates and propagate compute client config (#10182)

Now that we construct the TLS client config for cancellation as well as
connect, it feels appropriate to construct the same config once and
re-use it elsewhere. It might also help should #7500 require any extra
setup, so we can easily add it to all the appropriate call sites.

proxy/src/stream.rs

@@ -11,9 +11,9 @@ use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
 use tokio_rustls::server::TlsStream;
 use tracing::debug;
 
-use crate::config::TlsServerEndPoint;
 use crate::error::{ErrorKind, ReportableError, UserFacingError};
 use crate::metrics::Metrics;
+use crate::tls::TlsServerEndPoint;
 
 /// Stream wrapper which implements libpq's protocol.
 ///