Remove logic about where the whitehall mysql db is.
Remove logic about where the whitehall mysql db is.

We have moved off the interim platform. The whitehall DB is now on
its own cluster in all 3 environments. Therefore we no longer need
logic to decide where the alias should be.

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet