Added no-seed flag to yarn setup. (#19697)

refs https://ghost.slack.com/archives/C02G9E68C/p1707994528206559

- When running Ghost development and using MySQL + Docker, you can run
the command `yarn setup --no-seed` to not have the database seeded with
test data.

.github/scripts/setup.js

@@ -119,7 +119,11 @@ async function runAndStream(command, args, options) {
 
     console.log(chalk.blue(`Running knex-migrator init`));
     await runAndStream('yarn', ['knex-migrator', 'init'], {cwd: coreFolder});
-
+    if (process.argv.includes('--no-seed')) {
+        console.log(chalk.yellow(`Skipping seed data`));
+        console.log(chalk.yellow(`Done`));
+        return;
+    }
     if (resetData) {
         const xxl = process.argv.includes('--xxl');