paycheck: fix integration test script

Now that paycheck comes equipped with the Chrome OS standard public key
and infers metadata signature filenames automatically, we don't need
these extra arguments handed to the test script. Also, fixes a small bug
in option inference during paycheck invocation.

BUG=None
TEST=integration test script works as intended

Change-Id: If2c0d512c2e9476c3788e9c7179e954ba2502657
Reviewed-on: https://gerrit.chromium.org/gerrit/50985
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
diff --git a/scripts/paycheck.py b/scripts/paycheck.py
index de5a7e7..0ca2a76 100755
--- a/scripts/paycheck.py
+++ b/scripts/paycheck.py
@@ -121,7 +121,8 @@
   # There are several options that imply --check.
   opts.check = (opts.check or opts.report or opts.assert_type or
                 opts.block_size or opts.allow_unhashed or
-                opts.disabled_tests or opts.key or opts.meta_sig or
+                opts.disabled_tests or opts.meta_sig or
+                opts.key != default_key or
                 opts.root_part_size != _DEFAULT_ROOTFS_PART_SIZE or
                 opts.kern_part_size != _DEFAULT_KERNEL_PART_SIZE)