[EuiCard] Harden Click Event Criteria to Prevent Duplicate onClick Events

[breehall]

Fixes #6545

Summary

Resolved a bug that causes the onClick method to be triggered twice when clicking on a card title by creating a condition inside of outerOnClick to ensure the link does not contain a duplicate click event. Updated tests accordingly

QA

Testing:

1. Pull branch and open src-docs/src/views/card/card_beta.tsx. Update the first EuiCard instance (line 13) to:

<EuiCard
        icon={<EuiIcon size="xxl" type="dashboardApp" />}
        title={<span>Dashboards</span>}
        description="Example of a card's description. Stick to one or two sentences."
        onClick={() => {
          console.log('Dashboards Clicked');
        }}
        betaBadgeProps={{
          label: 'Beta',
          tooltipContent:
            'This module is not GA. Please help us by reporting any bugs.',
        }}
      />

2. Spin up EUI and navigate the the EuiCard Beta Badge example. When clicking on the title (Dashboards), you should find that the click event has only fired once, not twice.

General checklist

• Checked Code Sandbox works for any docs examples
• Added or updated jest and cypress tests
• Checked for breaking changes and labeled appropriately
• A changelog entry exists and is marked appropriately

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_6551/

[cee-chen]

Pull branch and open src-docs/src/views/card/card_beta.tsx. Update the first EuiCard instance (line 13) to:

Quick FYI for future PRs and QA - I'd suggest a [REVERT ME] commit where you commit the repro changes to the PR, and then git revert [commitId] at the end before merging the PR in. This makes it significantly easier for others to quickly QA your fixes etc. on staging without having to pull down your branch. An example PR with this: https://github.com/elastic/eui/pull/6543/commits

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_6551/

[cee-chen]

Woohoo, thanks for jumping on this Bree!