Purge some more perl tests.

- precommit is now shipped to the core tests along with state_3pc patch;
- truncate is expensive, exists for not clear goal and rarely bails out with
  deadlock which is expected (could be suppressed of course);
- dump_restore is too narrow;

And don't run init.pl normally, it is also compute-hungry.

Author: arssher

t/002_cross._pl renamed to t/000_cross._pl

@@ -1,5 +1,6 @@
 # test that after create_mm awaited nodes we won't get non-online state
 # immediately later. Catches races in MtmGetCurrentStatus logic.
+# It is expensive, so not run in the regular suite.
 
 use Cluster;
 use Test::More tests => 1;