xDS: add enum specified in xRFC TP3 in the right place

[markdroth]

Commit Message: xDS: add enum specified in xRFC TP3 in the right place
Additional Description: In #37818, I incorrectly added this new value to the deprecated location for this enum, not the real location. :(
Risk Level: Low
Testing: N/A
Docs Changes: Included in PR
Release Notes: N/A
Platform Specific Features: N/A

CC @adisuissa

[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: #37858 was opened by markdroth.

see: more, trace.

[adisuissa]

/lgtm api

Should this be removed from the deprecated enum?

[repokitteh-read-only]

🙀 Error while processing event:

evaluation error
error: function _github_call error: github error: POST https://api.github.com/repos/envoyproxy/envoy/statuses/3f77c291fb58b21409e62c9abef52bbac5a3f653: 500  []:
 Traceback (most recent call last):
  bootstrap:143: in <toplevel>
  bootstrap:135: in _main
  bootstrap:62: in _call
  bootstrap:15: in _call1
  github.com/envoyproxy/envoy/ci/repokitteh/modules/ownerscheck.star:275: in _lgtm_by_comment
  github.com/envoyproxy/envoy/ci/repokitteh/modules/ownerscheck.star:149: in _reconcile
  github.com/envoyproxy/envoy/ci/repokitteh/modules/ownerscheck.star:120: in _update_status
  github:572: in create_status
  github:155: in call
Error: function _github_call error: github error: POST https://api.github.com/repos/envoyproxy/envoy/statuses/3f77c291fb58b21409e62c9abef52bbac5a3f653: 500  []

🐱

Caused by: a #37858 (review) was submitted by @adisuissa.

see: more, trace.

[markdroth]

Should this be removed from the deprecated enum?

I think it's fine to leave it there. No one should use it, but it doesn't hurt anything.