fix(ui): replace Popover with Tooltip on disabled Register model button to fix focus trap

[Philip-Carneiro]

Description

Fixes an accessibility (a11y) regression on the Model Catalog Details page where keyboard focus (Tab) gets trapped on the disabled "Register model" button.
Root cause: The Popover component with triggerAction="hover" combined with isAriaDisabled on the button causes PatternFly's internal focus management to trap the Tab cycle, preventing users from navigating past the button.
Fix: Replace Popover with Tooltip for the disabled "Register model" button. The Tooltip provides the same hover information without interfering with keyboard focus management. The Popover used for the "Validated" label is unaffected and remains unchanged.

Before

Screen.Recording.2026-06-11.at.14.23.19.mov

After

Screen.Recording.2026-06-11.at.14.21.44.mov

How Has This Been Tested?

It was manually tested as the video sample and added tests in cypress for it

Merge criteria:

• All the commits have been signed-off (To pass the DCO check)

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If you have UI changes

• The developer has added tests or explained why testing cannot be added.
• Included any necessary screenshots or gifs if it was a UI change.
• Verify that UI/UX changes conform the UX guidelines for Kubeflow.

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[Philip-Carneiro]

/retest

[manaswinidas]

can we add a cy.testA11y() to double check all accessibility violations are gone?