fix: Tooltip Overlapping Charts due to a low z-index

[Sho-ki]

Description
This pull request addresses the issue where the tooltip overlaps surrounding charts due to a low z-index. The fix ensures that the tooltip has a higher z-index, preventing it from overlapping the charts and improving the overall user experience.

Related issue(s)
Fixes #1066

What kind of change does this PR introduce? (check at least one)

• Bug fix (non-breaking change which fixes an issue)
• New Feature (non-breaking change which adds functionality)
• New Feature (BREAKING CHANGE which adds functionality)
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes
• No

If yes, please describe the impact and migration path for existing applications:

How has this been tested?

• Manually tested the tooltip functionality across different browsers and screen sizes.
• Verified that the tooltip no longer overlaps with surrounding charts.
• Ensured that other elements' z-index are not adversely affected.

Screenshots (if appropriate):
Before:

After:

The PR fulfils these requirements:

• It's submitted to the main branch
• When resolving a specific issue, it's referenced in the related issue section above
• My change requires a change to the documentation. (Managed by Tremor Team)
• I have added tests to cover my changes
• Check the "Allow edits from maintainers" option while creating your PR.
• Add refs #XXX or fixes #XXX to the related issue section if your PR refers to or fixes an issue.
• By contributing to Tremor, you confirm that you have read and agreed to Tremor's CONTRIBUTING.md guideline. You also agree that your contributions will be licensed under the Apache License 2.0 license.

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Name	Status	Preview	Comments	Updated (UTC)
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[alexbalonperin]

It would be great if you could apply this fix to all chart types (e.g. LineChart, AreaChart, etc). 🙂

[Sho-ki]

Sure, I'll be working on it.

[Sho-ki]

I've fixed other chart types as well.