fix(card): remove onclick handler for pictogram (#12123)

### Related Ticket(s)

[ADCMS-6850](https://jsw.ibm.com/browse/ADCMS-6850)

### Description

Removes an `onclick` handler on cards which is redundant and hinders customization by adopters. The `onlick` handler here is already covered by the `<a>` that has an `::after` pseudo element covering the card and capturing the click event for sighted and non-sighted users.

The `onclick` handler was added back in #6642.

### Changelog

**Changed**

- Removed `onclick` handler from pictogram cards

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packages/web-components/src/components/card/card.ts

@@ -401,7 +401,6 @@ class C4DCard extends CTAMixin(StableSelectorMixin(CDSLink)) {
     }
 
     if (this._hasPictogram) {
-      this.onclick = () => window.open(this.href, '_self');
       this.setAttribute('pictogram', '');
     } else {
       this.removeAttribute('pictogram');