fix: Added z-index for table head

[albinAppsmith]

Description

Added z-index to sticky thead to avoid row components overlapping.

Fixes appsmithorg/appsmith#28014

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Manual on storybook
• Manual on main repo
• Jest
• Cypress

Checklist:

Dev activity

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

QA activity:

• Test plan has been approved by relevant developers
• Test plan has been peer reviewed by QA
• Cypress test cases have been added and approved by either SDET or manual QA
• Organized project review call with relevant stakeholders after Round 1/2 of QA
• Added Test Plan Approved label after reveiwing all Cypress test

[changeset-bot]

🦋 Changeset detected

Latest commit: e455013

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@appsmithorg/design-system-old	Patch

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Name	Status	Preview	Comments	Updated (UTC)
design-system	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Oct 24, 2023 5:39am

[albinAppsmith]

/generate-alpha

[github-actions]

Publish Result: @appsmithorg/[email protected]

[albinAppsmith]

/generate-alpha