AthenaServices: Add a convenience method for configuring the execution of conditions algorithms in AthenaMP PreFork

This MR adds a convenience method that configures the execution of conditions algorithms in the PreFork step of AthenaMP. This can be used as a postInclude in the derivation production jobs. So, instead of the current:

--postExec "default:cfg.getService(\"AthMpEvtLoopMgr\").ExecAtPreFork=[\"AthCondSeq\"];"

one would do:

--postInclude "default:AthenaServices.TransformUtils.ExecCondAlgsAtPreFork"

If there are configuration issues, e.g. trying to toggle this in serial Athena as reported in ATLASDPD-1801, the job will be able to carry on.

cc: @calpigia @jcatmore

Closes ATLASDPD-1801