Performance Profiler: fixes navbar position

[cpapazoglou]

Related to p58i-iWu-p2#comment-65329
Fixes #97457

Proposed Changes

• Puts the navbar lower in zindex stack so that admin bar popup links are shown.

Testing Instructions

• While logged in, visit https://wordpress.com/speed-test-tool?url=https%3A%2F%2Fwww.atliq.com%2F&hash=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpZCI6MzEyNTZ9.BbtHmgsX0GZ16YLe3aMS_dR3FIA4zLF4WyYXyjotts4
• Inspect that hovering over the Admin bar links, popups are shown

Before	After

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
  • For UI changes, have we tested the change in various languages (for example, ES, PT, FR, or DE)? The length of text and words vary significantly between languages.
• For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?

[github-actions]

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https://calypso.live?image=registry.a8c.com/calypso/app:build-127678

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https://calypso.live?image=registry.a8c.com/calypso/app:build-127678&env=jetpack

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https://calypso.live?image=registry.a8c.com/calypso/app:build-127678&env=a8c-for-agencies

[epeicher]

This tests well, I can see the popup on top of the button now. LGTM!

[matticbot]

This PR does not affect the size of JS and CSS bundles shipped to the user's browser.

Generated by performance advisor bot at iscalypsofastyet.com.

[matticbot]

This PR modifies the release build for the following Calypso Apps:

For info about this notification, see here: PCYsg-OT6-p2

• notifications
• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug fix/performance-profiler-nav-bar-position on your sandbox.