zephyr: twister: Disable argparse prefix matching
zephyr: twister: Disable argparse prefix matching

This "feature" of argparse messes with our argument processing and
causes `--test` to be interpreted as `--testsuite-root` due to common
prefix matching. Verified that --test args get passed straight through.

BUG=b:240093007
BRANCH=None
TEST=./twister --test foo -v

Signed-off-by: Tristan Honscheid <1e17951ff5ffc8afe254954c03de64afef62fe52@google.com>
Change-Id: Ia849c5c270954799e93cbbfbae232624e2faa8f6
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3824958
Reviewed-by: Jeremy Bettis <4df7b5147fee087dca33c181f288ee7dbf56e022@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec