protected void preserveDTMService(Program program) {
		if (program != null) {
			// do not dispose analysis manager since we want to keep DTM service alive
			AutoAnalysisManager analysisMgr = AutoAnalysisManager.getAnalysisManager(program);
			setInstanceField("service", analysisMgr, null);
		}
	}
Setup DTM service such that the same instance if used across all test methods.
This assumes that a tool is not used and that the DefaultDataTypeManagerService 
is used.
Ghidra/Features/MicrosoftCodeAnalyzer/src/test/java/ghidra/app/cmd/data/AbstractCreateDataTypeModelTest.java