Prevent concurrent execution of some tests

when running tests in parallel I had failures on a few tests because they were stepping on each other.

The correct fix would be to change the tests so that they do not clash, but serializing the execution is a valid workaround until somebody wants to correctly tackle the problem.

Kernel/LHCbAlgs/tests/qmtest/lhcbalgs.qms/runchange.qms/handler_samefile_newdata.qmt

@@ -84,4 +84,7 @@ if outputlines != expected:
     causes.append("output")
     result["GaudiTest.output.found"] = result.Quote("\n".join(outputlines))
 </text></argument>
+<argument name="prerequisites"><set>
+  <tuple><text>lhcbalgs.runchange.handler_newfile_samedata</text><enumeral>PASS</enumeral></tuple>
+</set></argument>
 </extension>