Stop using trigger_reset_main.

This trigger was used on FDE devices to bring down the minimal
framework, and worked by shutting down the 'main' service class.

With APEX being introduced, we want to restart all services that were
started after the tmpfs /data was mounted, as those are the services
that haven't been able to use updated APEXes in the (real) /data.

In order to do this, we need to reset more classes; that in turn
made the 'shutdown_main' trigger pretty much similar to the
previously existing 'trigger_shutdown_framework' trigger; so instead
of keeping two duplicate triggers, use only the
'trigger_shutdown_framework' one.

Bug: 118485723
Test: Taimen configured as FDE boots, Taimen configured as FBE boots
Change-Id: I0d80ef2528bd70870b063a2c580cd00a03de9961