Fix shredder load order in sbin/rt-shredder.in, as t/shredder/utils.pl

be66534 fixed the load order in the file used to test RT::Shredder, but
neglected to fix the execution path called by sbin/rt-shredder itself.
Because of Shredder's unconventional load order (loading the majority of
package via RT::Shredder's BEGIN via the RT::Shredder::RecordName
packages -- instead via RT->Init), this causes the following:

    $ /opt/rt4/sbin/rt-shredder

    Can't locate object method "CustomFieldLookupType" via package "RT::Ticket" at /opt/rt4/sbin/../lib/RT/Tickets.pm line 1382.
    Compilation failed in require at /opt/rt4/sbin/../lib/RT/Ticket.pm line 78.
    BEGIN failed--compilation aborted at /opt/rt4/sbin/../lib/RT/Ticket.pm line 78.
    Compilation failed in require at /opt/rt4/sbin/../lib/RT/Shredder/Ticket.pm line 49.
    BEGIN failed--compilation aborted at /opt/rt4/sbin/../lib/RT/Shredder/Ticket.pm line 49.
    Compilation failed in require at /opt/rt4/sbin/../lib/RT/Shredder.pm line 230.
    BEGIN failed--compilation aborted at /opt/rt4/sbin/../lib/RT/Shredder.pm line 233.
    Compilation failed in require at /opt/rt4/sbin/rt-shredder line 138.
    BEGIN failed--compilation aborted at /opt/rt4/sbin/rt-shredder line 138.

Switch to the now-standard "use RT -init" which calls RT->LoadConfig and
RT->Init at compile-time.  This also requires the removal of
RT::Shredder::Init, which would otherwise call them again at run-time.
While both should be idempotent, there is no reason to do so -- the %opt
which is stored in RT::Shredder::Init is never used, and thus the entire
call is safe to be removed.
Merge branch '4.0/shredder-load-order' into 4.0.16-releng
Merge branch '4.0.16-releng' into 4.0-trunk