chore: set unleash version to be either the enterprise version or OSS (…

…#3974)

## About the changes
Unleash version should be the one best representing its runtime. In this
regard, enterpriseVersion trumps unleash-server version.

This version is the one that's sent as part of our metrics.

src/lib/server-impl.ts

@@ -39,7 +39,7 @@ async function createApp(
 ): Promise<IUnleash> {
     // Database dependencies (stateful)
     const logger = config.getLogger('server-impl.js');
-    const serverVersion = version;
+    const serverVersion = config.enterpriseVersion ?? version;
     const db = createDb(config);
     const stores = createStores(config, db);
     const services = createServices(stores, config, db);