test: support TEST_NO_QEMU in mkosi integration wrapper

Same as the old integration test suite, allow skipping tests that
require qemu.
ppc64el's vsock support doesn't appear to work, so we'll skip it,
as it is already done in the legacy framework.

test/integration-test-wrapper.py

@@ -57,6 +57,10 @@ def main():
         print(f"SYSTEMD_SLOW_TESTS=1 not found in environment, skipping {args.name}", file=sys.stderr)
         exit(77)
 
+    if args.vm and bool(int(os.getenv("TEST_NO_QEMU", "0"))):
+        print(f"TEST_NO_QEMU=1, skipping {args.name}", file=sys.stderr)
+        exit(77)
+
     name = args.name + (f"-{i}" if (i := os.getenv("MESON_TEST_ITERATION")) else "")
 
     dropin = textwrap.dedent(