This PR updates the tags that we generate for Envoy stats.
Several of these come with breaking changes, since we can't keep two stats prefixes for a filter.
This has the biggest impact on enterprise test cases that use namespaced
registrations, which prior to this change sometimes failed the initial
registration because the namespace was not yet created.
* Expose Envoy /stats for statsd agents; Add testcases
* Remove merge conflict leftover
* Add support for prefix instead of path; Fix docstring to mirror these changes
* Add new config field to docs; Add testcases to check that /stats/prometheus is exposed as well
* Parametrize matchType (prefix or path) and value
* Update website/source/docs/connect/proxies/envoy.md
Co-Authored-By: Paul Banks <banks@banksco.de>
Co-authored-by: Paul Banks <banks@banksco.de>
