[Mule Migration tool] Invalid regex pattern generation

### Description

```
<file:matcher filenamePattern="*.csv" regularFiles="REQUIRE"/>
```

For the above code, an invalid regex pattern is generated, as shown below.
```
regex:matches(event.name, ".*\.csv")
```

### Steps to Reproduce

Run the above code.

### Version

WI: 5.0.0

### Environment Details (with versions)

_No response_