service: for Type=idle units consider START_PRE, START, START_POST all as ACTIVE

service: for Type=idle units consider START_PRE, START, START_POST all as ACTIVE

We want to avoid a deadlock when a service has ExecStartPre= programs
that wait for the job queue to run empty because of Type=idle, but which
themselves keep the queue non-empty because START_PRE was considered
ACTIVATING and hence the job not complete. With this patch we alter the
state translation table so that it is impossible ever to wait for
Type=idle unit, hence removing the deadlock.