[Components][Form] Fixed version specific examples of some form events.

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    |  2.3
| Fixed tickets | 

* Examples that point to DataCollectorListener (added since 2.4) should be removed (or adapted when it's possible).
* This fix <b>only</b> applies to 2.3.