Context:
* https://wikitech.wikimedia.org/wiki/Mw-experimental
* https://wikitech.wikimedia.org/wiki/WikimediaDebug#Plaintext_CLI_profile
* {T276994}, {T396767}, {T397498}
* {T341553}
When SSH-ing to `mw-experimental` one currenty ends up on the kubernetes host, not the pod where PHP is installed.
This means only files for web requests can be debugged and ad-hoc changed (e.g. via browser or curl), not files executed via maintenance scripts. This was something I would do monthly or so on the mwdebug hosts when debugging something, whether via `php MWScript.php eval.php` or via an existing maintenance script.
Is there a supported way to start a shell inside the mw-experimental pod?
Use cases:
* Iterate on a draft wmf-config change in `/srv/mediawiki/wmf-config` and review runtime impact via `mwscript eval.php`.
* Debug a maintenance script by making ad-hoc changes under `/srv/mediawiki/php-/maintenance/` or `/srv/mediawiki/php-/extensions/*/maintenance/`, and run `mwscript something.php`.
* Profiling, per https://wikitech.wikimedia.org/wiki/WikimediaDebug#Plaintext_CLI_profile.