[Feature Request]: when opening up a table input with an invalid connection

### What would you like to happen?

When opening up a table input (starting in v 2.11) and the db connection is not valid, you just get a spinning icon until it opens up 20 seconds (or so) later. It would be beneficial to include the information that caused the transform to open up delayed. This would be similar when testing a db connection and get an error.

### Issue Priority

Priority: 3

### Issue Component

Component: Transforms

Start by reproducing the table-input flow introduced in version 2.11 with an invalid database connection, then compare it with the existing database connection test error behavior. Done means the table input reports the connection failure information instead of showing only a spinner for roughly 20 seconds.

Written by the indexing model from the issue text.