Core: Minimize await to a single JS cycle (refactor #21186)

[nielslyngsoe]

Minimize the disconnect-debounce to use a single JS cycle instead of a whole rendering frame.

Refactor / continued work of #21186

[Copilot]

Pull request overview

Refactors several disconnect/deferred-destruction paths to avoid waiting a full rendering frame, using a single JS-cycle (microtask) cancellation pattern instead. This supports the extension slot lifecycle behavior needed during DOM moves/sorting (continuation of #21186).

Changes:

• Replaced requestAnimationFrame-based disconnect debouncing with a microtask (Promise.resolve().then(...)) + AbortController cancellation in multiple components.
• Updated extension slot elements to cancel pending teardown on reconnect using the new AbortController pattern.
• Refactored UmbContextConsumer disconnect handling and “listening scope” management to align with the new single-cycle behavior.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

File	Description
src/Umbraco.Web.UI.Client/src/packages/core/lit-element/directives/destroy.lit-directive.ts	Switches directive teardown deferral from rAF to microtask + AbortController.
src/Umbraco.Web.UI.Client/src/packages/core/extension-registry/components/extension-with-api-slot/extension-with-api-slot.element.ts	Updates deferred controller destruction to microtask + AbortController cancellation.
src/Umbraco.Web.UI.Client/src/packages/core/extension-registry/components/extension-slot/extension-slot.element.ts	Updates deferred destruction/event listener cleanup to microtask + AbortController cancellation.
src/Umbraco.Web.UI.Client/src/libs/context-api/consume/context-consumer.ts	Refactors disconnect cancellation and current “scope” event listening to avoid rAF usage.