OTel Access Logger: support custom stat prefix

[TAOXUY]

As described in the API, this allows to distinguish emitted statistics between configured open telemetry access loggers in the logger chain. If empty, the default access_logs.open_telemetry_access_log. will be used.

It is based on https://github.com/envoyproxy/envoy/pull/34072 so please review from the 4th commit.

[repokitteh-read-only[bot]]

CC @envoyproxy/api-shepherds: Your approval is needed for changes made to (api/envoy/|docs/root/api-docs/). envoyproxy/api-shepherds assignee is @adisuissa CC @envoyproxy/api-watchers: FYI only for changes made to (api/envoy/|docs/root/api-docs/).

:cat:

Caused by: https://github.com/envoyproxy/envoy/pull/34091 was opened by TAOXUY.

see: more, trace.

[yanavlasov]

I will review once #34072 is submitted. /wait

[TAOXUY]

Please add a release note.

DONE