Unit tests skip code paths for parallel_script_checks==false

[hebasto]

The Chainstate::ConnectBlock() function is implemented in a way that different code paths are used during runtime depending on the parallel_script_checks flag's value.

OTOH, the current test suit implementation with the following lines:

bitcoin/src/test/util/setup_common.cpp

Lines 189 to 190 in e9262ea

	constexpr int script_check_threads = 2;
	StartScriptCheckWorkerThreads(script_check_threads);

sets the parallel_script_checks to true for all cases.

For example, the outcome of miner_tests is affected by the parallel_script_checks flag's value.

[kevkevinpal]

So do we want to modify the unit test to run miner_tests with both parallel_script_checks with both true and false?

or are there any other alternatives