Restore use-cache as default

[davidd-amd]

@AlexBrownAMD observed that tensilelt was significantly slower than tensile when running as follows:

./Tensile/Bin/Tensile test.yaml tensile-out

Profiling revealed that writeBenchmarkFiles was called by tensilelt leading to the additional runtime. The reason for this is because --use-cache was changed to false in #410. It isn't clear if this was the intention because store_true has the effect of setting the arg to False.

In this PR, we restore the default to True and correct issues that arose now that we are following a different code path.