Long custom severity labels don't fit in condition configuration form dialog.

Steps to reproduce:

1. Go to Administration=>General=>Trigger displaying options
2. Change severities name ( maxlength = 32)
3. Go to Configuration=>Actions=>Trigger actions=>Create action=>
   Conditions=>Add
4. Check trigger severities

Result: Long custom severity labels don't fit in condition configuration form dialog.
Expected: severity labels should fit form size.