Incident issue creation failed due to slack api errors

Summary

Due to Slack API errors production#6106 (closed) we were unable to declare an incident using Woodhouse, it looks like we failed outright when we weren't able to create the slack channel. Instead, we should create the incident issue and skip the channel creation.

{"async_job_name":"create_incident","duration_s":1.250553887,"error":"error creating slack channel: fatal_error","event":"async_job_complete","image_size":"192","job":"create_incident","level":"info","status":"error","ts":"2021-12-22T13:25:28.449004514Z"}

Originating issue(s): production#6106 (closed)

Desired Outcome/Acceptance criteria

Associated Services

Corrective Action Issue Checklist

• link the incident(s) this corrective action arose out of
• give context for what problem this corrective action is trying to prevent from re-occurring
• assign a severity label (this is the highest sev of related incidents, defaults to 'severity::4')
• assign a priority (this will default to 'priority::4')