CTest: multiple ctest_test calls w/LABEL regexs (#11487)

The Initialize method was not re-initializing everything
that it should have been. This commit fixes that.

Source/CTest/cmCTestTestHandler.cxx

@@ -438,6 +438,8 @@ void cmCTestTestHandler::Initialize()
 
   this->TestsToRun.clear();
 
+  this->UseIncludeLabelRegExpFlag = false;
+  this->UseExcludeLabelRegExpFlag = false;
   this->UseIncludeRegExpFlag = false;
   this->UseExcludeRegExpFlag = false;
   this->UseExcludeRegExpFirst = false;