Add arity = 1 to --reuse-output-dirs
Add arity = 1 to --reuse-output-dirs

In this way, users can specify --reuse-output-dirs=false

PiperOrigin-RevId: 159831497
Change-Id: I779c533ccccd0805ee2d2f147c03ee1b95742e25

google/copybara,google/copybara,google/copybara