chore(recovery-key): Remove all recovery key experiment code.

[shane-tomlinson]

Recovery keys are a full feature, there is no longer a need
to retain the experiment code and gating logic.

Not attached to an issue, I noticed when looking at the latest recovery email text and it still has the ?showRecoveryKey query parameter.

@vbudhram - r?

[vbudhram]

@shane-tomlinson This LGTM 👍. @irrationalagent I know that we have an airtable feature to track the long affects of the change, if we remove the experiment can we still track it?

[shane-tomlinson]

@irrationalagent from Slack:

As long as the flow events still fire, we no longer need the cohorting @stomlinson

[shane-tomlinson]

3|content-server PORT 3030  | {"event":"flow.settings.account-recovery.recovery-key.view","flow_id":"a56a17dbc910c013b7c9f4cedfeec65ec15017f0a886a9cdb49f403f29d3aef9","flow_time":15199,"hostname":"stomlinson-30887","locale":"es_ES","op":"flowEvent","pid":52513,"time":"2018-12-21T20:45:41.736Z","userAgent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:66.0) Gecko/20100101 Firefox/66.0","v":1,"context":"fx_desktop_v3","entrypoint":"menupanel","service":"sync"}
...
3|content-server PORT 3030  | {"event":"flow.settings.account-recovery.recovery-key.copy-option","flow_id":"a56a17dbc910c013b7c9f4cedfeec65ec15017f0a886a9cdb49f403f29d3aef9","flow_time":39698,"hostname":"stomlinson-30887","locale":"es_ES","op":"flowEvent","pid":52513,"time":"2018-12-21T20:46:06.235Z","userAgent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:66.0) Gecko/20100101 Firefox/66.0","v":1,"context":"fx_desktop_v3","entrypoint":"menupanel","service":"sync"}
....
3|content-server PORT 3030  | {"event":"flow.account-recovery-confirm-key.view","flow_id":"5f80923e932a9f8b06595fbb5d3ee652f6f0ce06eea4138a12fe683af9649db5","flow_time":24583,"hostname":"stomlinson-30887","locale":"es_ES","op":"flowEvent","pid":52513,"time":"2018-12-21T20:47:41.983Z","userAgent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:66.0) Gecko/20100101 Firefox/66.0","v":1,"context":"fx_desktop_v3","entrypoint":"menupanel","service":"sync","utm_campaign":"fx-forgot-password","utm_content":"fx-reset-password","utm_medium":"email"}
3|content-server PORT 3030  | {"event":"flow.account-recovery-confirm-key.engage","flow_id":"5f80923e932a9f8b06595fbb5d3ee652f6f0ce06eea4138a12fe683af9649db5","flow_time":66244,"hostname":"stomlinson-30887","locale":"es_ES","op":"flowEvent","pid":52513,"time":"2018-12-21T20:48:23.644Z","userAgent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:66.0) Gecko/20100101 Firefox/66.0","v":1,"context":"fx_desktop_v3","entrypoint":"menupanel","service":"sync","utm_campaign":"fx-forgot-password","utm_content":"fx-reset-password","utm_medium":"email"}
3|content-server PORT 3030  | {"event":"flow.account-recovery-confirm-key.submit","flow_id":"5f80923e932a9f8b06595fbb5d3ee652f6f0ce06eea4138a12fe683af9649db5","flow_time":66871,"hostname":"stomlinson-30887","locale":"es_ES","op":"flowEvent","pid":52513,"time":"2018-12-21T20:48:24.271Z","userAgent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:66.0) Gecko/20100101 Firefox/66.0","v":1,"context":"fx_desktop_v3","entrypoint":"menupanel","service":"sync","utm_campaign":"fx-forgot-password","utm_content":"fx-reset-password","utm_medium":"email"}
3|content-server PORT 3030  | {"event":"flow.account-recovery-confirm-key.success","flow_id":"5f80923e932a9f8b06595fbb5d3ee652f6f0ce06eea4138a12fe683af9649db5","flow_time":67105,"hostname":"stomlinson-30887","locale":"es_ES","op":"flowEvent","pid":52513,"time":"2018-12-21T20:48:24.505Z","userAgent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:66.0) Gecko/20100101 Firefox/66.0","v":1,"context":"fx_desktop_v3","entrypoint":"menupanel","service":"sync","utm_campaign":"fx-forgot-password","utm_content":"fx-reset-password","utm_medium":"email"}
3|content-server PORT 3030  | {"event":"flow.account-recovery-reset-password.view","flow_id":"5f80923e932a9f8b06595fbb5d3ee652f6f0ce06eea4138a12fe683af9649db5","flow_time":67152,"hostname":"stomlinson-30887","locale":"es_ES","op":"flowEvent","pid":52513,"time":"2018-12-21T20:48:24.552Z","userAgent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:66.0) Gecko/20100101 Firefox/66.0","v":1,"context":"fx_desktop_v3","entrypoint":"menupanel","service":"sync","utm_campaign":"fx-forgot-password","utm_content":"fx-reset-password","utm_medium":"email"}

Flow events are still there!