release: ifdef compile ESRP steps (#2241)

Move from a runtime `condition` on the ESRP steps to a YAML parse-time
condition so that no usage of the `esrp*ConnectionName` variables exist
when the esrp parameter is false.

This means we can avoid the need to approve runs of this workflow in the
internal secure environment when not accessing ESRP (for example, when
debugging and testing the release process).

Author: mjcheetham