Database drop-down menu extremely slow

### Description

Hello, we work with over 2000 databases and have the problem that the drop-down menu for database selection opens extremely slowly. Sometimes the page has to be reloaded in the browser. We use this database selection after opening shared SQL scripts.

### Steps to reproduce

1. Open a database connection from left menu - shared connections.
2. Open a shared SQL script.
3. Try to select the active database connection from drop down menu.
4. Response is very slow, probably because of 2000 shared databases connections

### Expected/Desired Behavior

The drop-down menu should open immediately.
I suggest that only all active database connections are displayed here or that the list is limited to the top 50.

### CloudBeaver Version

Cloud Beaver Community 25.1.5

### Additional context

Open Shift Environment. 2 Pod Replicas with shared NFS storage.

No implementation file or test is named. Reproduce the delay by opening a shared SQL script and its database selector with more than 2,000 shared connections, then trace the selector's loading path and measure its response; done means the menu opens promptly while displaying the agreed connection set.

Written by the indexing model from the issue text.