Move pipeline header actions to panel header portal

What does this MR do and why?

Migrates the pipeline detail page header actions (retry, cancel, delete, and fix-with-Duo) into the shared panel header actions region via PanelActionsPortal, instead of rendering them inline in the page heading #actions slot.

This follows the same pattern used for the job details page and work items, giving the pipeline page consistent action placement in the panel header. @force_show_panel_header = true is set on the pipeline view so the portal target is always rendered.

Changes:

• Wraps the #actions slot content in PanelActionsPortal; drop gl-self-start classes that no longer apply in the centered panel header.
• Delete button becomes a tertiary icon-only button (aligns it with Jobs)
• Anchored tooltips for actions to the bottom

References

• gitlab-org/upstream-studios/design-strategy/craft-quotient#41

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Visit any pipeline detail page, for example https://gdk.test:3000/flightjs/Flight/-/pipelines/571
2. Confirm the retry/cancel/delete actions render in the panel header actions area (top of the panel) rather than inline next to the pipeline title.
3. Exercise retry, cancel, and delete and confirm they behave as before.

MR acceptance checklist

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