test: avoid mustCall mismatch in SEA zip test

Run the synchronous SEA build and execution inside the promise callback. The
callback is then counted before buildSEA can skip the test when signing tools
are unavailable.

Signed-off-by: Matteo Collina <hello@matteocollina.com>
Assisted-by: Pi

Author: mcollina

test/sea/test-single-executable-application-vfs-zip.js

@@ -35,7 +35,9 @@ async function main() {
     ]),
     createWriteStream(tmpdir.resolve('assets.zip')),
   );
+}
 
+main().then(common.mustCall(() => {
   const outputFile = buildSEA(fixtures.path('sea', 'vfs-zip'));
 
   spawnSyncAndAssert(
@@ -55,6 +57,4 @@ async function main() {
       },
     },
   );
-}
-
-main().then(common.mustCall());
+}));