Add a test for issue 100 in DaVinciTests

Closes #100 (closed).

The test is a shorter version of the original script focusing only on what was giving trouble.

DaVinciTests/python/DaVinciTests/mc/option_davinci-issue-100_multiple_bkgcat_mc-truth.yaml

 input_files:
   - root://eoslhcb.cern.ch//eos/lhcb/wg/dpa/wp3/tests/test_davinci-issue-100_multiple_bkgcat_mc-truth.dst
-input_manifest_file: '/eos/lhcb/wg/dpa/wp3/tests/test_davinci-issue-100_multiple_bkgcat_mc-truth.tck.json'
+input_manifest_file: /eos/lhcb/wg/dpa/wp3/tests/test_davinci-issue-100_multiple_bkgcat_mc-truth.tck.json
 
-data_type: 'Upgrade'
+data_type: Upgrade
 input_type: ROOT
 simulation: True
-input_process: 'Hlt2'
+input_process: Hlt2
 
 conddb_tag: sim-20210617-vc-md100
 dddb_tag: dddb-20210617
@@ -13,5 +13,3 @@ dddb_tag: dddb-20210617
 evt_max: -1
 input_raw_format: 0.3
 lumi: false
-
-ntuple_file: davinci-issue-100_multiple_bkgcat_mc-truth_ntuple.root