unhide custom settings option in protocol options

[ramaraochavali]

This has been implemented by #9964
Commit Message:unhide custom settings option
Additional Description:unhide custom settings option in protocol options
Risk Level:N/A
Testing:N/A
Docs Changes:N/A
Release Notes:N/A
Platform Specific Features:
[Optional Runtime guard:]
[Optional Fixes #Issue]
[Optional Fixes commit #PR or SHA]
[Optional Deprecated:]
[Optional API Considerations:]

[repokitteh-read-only]

CC @envoyproxy/api-shepherds: Your approval is needed for changes made to (api/envoy/|docs/root/api-docs/).
envoyproxy/api-shepherds assignee is @mattklein123
CC @envoyproxy/api-watchers: FYI only for changes made to (api/envoy/|docs/root/api-docs/).

🐱

Caused by: #22376 was opened by ramaraochavali.

see: more, trace.

[ramaraochavali]

/retest

[repokitteh-read-only]

Retrying Azure Pipelines:
Retried failed jobs in: envoy-presubmit

🐱

Caused by: a #22376 (comment) was created by @ramaraochavali.

see: more, trace.

[zuercher]

Reassigned @lizan as api shepherd

[lizan]

I don't have the original PR context, @alyssawilk did the deprecation PR described https://github.com/envoyproxy/envoy/pull/9964/files#r394441848 happen?

[alyssawilk]

allow_connect doesn't look deprecated so I'm going with "no"
I think to unhide this, we should deprecate allow_connect, and config-check that if custom_settings_parameters is used, that allow_connect is not true, and update the comments for this field as well as relevant docs.

[ramaraochavali]

Oh. I did not know the dependency on allow_connect. Will close this PR.