Some regexps make it difficult to cancel a search

### Description

Currently, search can be canceled using the red "Stop Search" button, but at least using regex search, the cancel action is not processed immediately and it seems Netbeans waits until the currently searched file is processed completely.

Reproducible with `".*,.*,.*,.*,.*,13,.*,.*,.*,.*,.*,.*"` slow regex basically on any larger codebase.

### Use case/motivation

When a complex regex is used on a large file, the current solution is to restart Netbeans to cancel the search operation. This is of course unacceptable for regular work.

### Related issues

_No response_

### Are you willing to submit a pull request?

No

Start by reproducing the slow regex search in NetBeans using the example pattern on a large codebase, then trace the Stop Search cancellation path. Done means cancellation interrupts processing promptly instead of waiting for the current file or requiring a restart.

Written by the indexing model from the issue text.