systemctl: prolong timeout of "systemctl daemon-reload"

systemctl: prolong timeout of "systemctl daemon-reload"

Reloading or reexecuting PID 1 means the unit generators are rerun, which are
timed out at 90s. Make sure the method call asking for the reload is timed out
at twice that, so that the generators have 90s and the reload operation has 90s
too.

This reworks the daemon_reload() call in systemctl, and makes it exclusively
about reloading/reexecing. Previously it was used for other trivial method
calls too, which didn't really help readability. As the code paths are now
sufficiently different, split out the old code into a new function
trivial_method().

This call also does a similar change as
c8ad4efb277c3235d58789170af11bb3c847d655 but for the reload/reexec operation.

Fixes: #3353