fix(test): only run external migrations when indexer is enabled

MSP nodes have SH_INDEXER_DB_AUTO_MIGRATE enabled by default and handle
their own database migrations internally during startup. External migrations
using the diesel CLI should only run for user nodes with embedded indexer
(which have auto-migrate disabled via SH_INDEXER_DB_AUTO_MIGRATE="false").

This fixes CI test failures where diesel CLI is not installed on the runner,
causing "Error running Diesel CLI" when fullnet tests try to run external
migrations that are redundant (MSPs already migrated themselves).

Before: External migrations ran for fullnet OR indexer
After: External migrations only run for indexer

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: snowmead

test/util/netLaunch/index.ts

@@ -380,8 +380,9 @@ export class NetworkLauncher {
         log: verbose
       });
 
-      // Run migrations for fullnet (MSPs need the schema) or when indexer is enabled
-      if (this.type === "fullnet" || this.config.indexer) {
+      // Only run external migrations when indexer enabled
+      // (MSPs and standalone indexer auto-migrate themselves)
+      if (this.config.indexer) {
         await this.runMigrations();
       }