v2.155.0

This release features some performance improvements: tokio has been
updated to pick up tokio-rs/tokio#4055, and link-time optimizations have
been enabled in release builds. These changes reduce CPU and memory
overhead in benchmarks.

Inbound policy enforcement has been updated so that TCP forwarding is
interrupted if a policy update revokes a previously-established
authorization. New metrics are exposed to reflect how policies are used
by the proxy: `inbound_http_authz_{allow,deny}_total` and
`inbound_tcp_authz_{allow,deny,terminate}_total`.

The proxy's error metrics, `{inbound,outbound}_{http,tcp}_errors_total`,
have been updated to include the traffic target. And the `traffic_addr`
metric label is augmented by `target_ip` and `target_port` labels to
support more flexible prometheus queries.

Inbound TCP metrics now only include a `srv_name` label, as it can't be
expected for all inbound connections to include authorization labels
(hence the new authz metrics). However, all inbound HTTP metrics--except
for the HTTP errors metric, which includes only a `srv_name`
label--include both `srv_name` and `saz_name` label.

Finally, the inbound and outbound proxies now only exports
Route-oriented metrics when a ServiceProfile is enabled, preventing
redundant metrics from being exported with no differentiating labels.