pw_system: Remove use of BooleanOptionalAction
pw_system: Remove use of BooleanOptionalAction

Remove use of argparse.BooleanOptionalAction which isn't supported by
Python 3.8.

Change-Id: I1d7ea1dbf6045f620604d6c9e970fd622ed98a69
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/111671
Commit-Queue: Auto-Submit <14637eda5603879df170705285bf30f5996692f0@pigweed.google.com.iam.gserviceaccount.com>
Pigweed-Auto-Submit: Rob Mohr <d07614a8a0b466db08f68224f87d738b0f9615cf@google.com>
Reviewed-by: Anthony DiGirolamo <4cc40125edc24ec5bc72df7917ea0b403ee8cebe@google.com>

google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed