In order to support stateless systems that support offline /usr updates
properly, let's restore the ConditionNeesUpdate=/etc line that makes sure we
are run when /usr is updated and this update needs to be propagated to the
/etc/ld.so.conf file stored in /etc.
This reverts part of #2859, which snuck this change in, but really shouldn't
have.
Also drop ConditionNeedsUpdate=|/etc. Regardless if system is updated
online or offline, updating dynamic loader cache should always be
responsibility of packaging tools/scripts.
Yu Watanabe