Stringent UT hits comparison between HLT1 vs HLT2

Made the test for UT hits comparison between HLT1 and HLT2 more stringent. The current test only search for WARNING, ERROR and FATAL.

This MR:

1. We require 100% overlap of UT hit LHCbID between HLT1 and HLT2.
2. Same number of UT hits matched to MC hits every time we test.
3. Test fails when UT LHCbIDs is duplicated within an event. This should help bug catching in UT decoding.

Works with Allen!1663 (merged). Requires a new reference file.

FYI: @dovombru @mveghel @hawu @ldufour @msaur

Hlt/RecoConf/tests/qmtest/decoding.qms/compare_hlt1_hlt2_ut_decoding_with_mcchecking.qmt

@@ -16,6 +16,7 @@
     <text>$RECOCONFROOT/options/compare_hlt1_hlt2_ut_hits_with_mcchecking.py</text>
   </set></argument>
   <argument name="reference"><text>../refs/compare_hlt1_hlt2_ut_decoding_with_mcchecking.ref</text></argument>
+  <argument name="error_reference"><text>../refs/empty.ref</text></argument>
   <argument name="validator"><text>
 
 from Moore.qmtest.exclusions import ref_preprocessor