[EuiComboBox] Remove Pill delete button is not accessible from the keyboard

[alexwizp]

Description:
This issue is associated with GitHub issue #196825 in the Elastic Kibana repository. Upon investigation, it is confirmed that pressing the Enter key does not trigger the corresponding removal action. This behavior does not align with WCAG 2.1.1 Keyboard Accessibility (Level A) guidelines, which stipulate that all functions should be accessible by keyboard alone.

Current Workaround:
Users can press the Space key as a temporary alternative. However, this solution may not be intuitive and is suitable only as a short-term.

Root Cause:
The issue appears to originate in the packages/eui/src/components/combo_box/combo_box.tsx file. The following lines prevent the Enter key from triggering the expected action. While removing these lines resolves the issue, the original purpose of this code is unclear, and further review may be needed to ensure it does not disrupt other functionalities.

 case keys.ENTER:
-       event.preventDefault();
-       event.stopPropagation();
        if (this.hasActiveOption()) {
          this.onAddOption(
            this.state.matchingOptions[this.state.activeOptionIndex]
          );
        } else {
          this setCustomOptions(false);
        }
        break;