RFE: Expose /debug/ on Docker Compose

Created by: mike-r-mclaughlin

Requested by: https://github.com/sourcegraph/accounts/issues/6716 via Slack

Feature request description

Expose /debug/ (i.e., "Instrumentation") on Docker Compose deployments.

Is your feature request related to a problem? If so, please describe.

Some customers cannot easily get console access to their Sourcegraph deployment. The /debug/ endpoint provides many useful features to do things that otherwise require console. For example, we need to run the Manual Purge operation to clean up disk space.

Additional context

Internal Slack discussion thread.