Revert "OXDEV-8213 Mentioned new comparisons in StringFilter"

This reverts commit 65d28d1.

Author: MarcelOxid

CHANGELOG-v9.md

@@ -7,7 +7,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [9.1.0] - Unreleased
 
 ### Added
-- Functionality for `equals` and `beginsWith` comparisons using `StringFilter`.
 - `DataType\Filter\AbstractNumberFilter`
 - `DataType\Filter\StringFilter::matches()` to check if string match the filter conditions