Formally deprecate *_METADATA access log command operators

[jbohanon]

Title: Formally deprecate *_METADATA access log command operators

Description:
The documentation for the command operators for access log formatting DYNAMIC_METADATA and CLUSTER_METADATA has indicated that these will be deprecated in favor of the METADATA formatter since the latter was implemented. We should actually deprecate these and make plans for their removal.

Relevant Links:
https://github.com/envoyproxy/envoy/pull/17457/files#diff-a5eb61dd3a95c605846ebaba934b7334bc18f96fbf9ebf7593a90948c92f19c5

[cpakulski]

Correct, this has been on my plate for a while, so I can drive deprecation. METADATA is right now an extension and I believe that in order to deprecate *_METADATA, the generic formatted must be moved out of extensions to core formatters.

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed in the next 7 days unless it is tagged "help wanted" or "no stalebot" or other activity occurs. Thank you for your contributions.

[jbohanon]

@cpakulski is this actively in progress or should we tag it help-wanted

[cpakulski]

@jbohanon Thanks for reminding. It will be done for the next release.

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed in the next 7 days unless it is tagged "help wanted" or "no stalebot" or other activity occurs. Thank you for your contributions.