release: ifdef compile ESRP steps

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).

Signed-off-by: Matthew John Cheetham <mjcheetham@outlook.com>

Author: mjcheetham