Fix ViewTransition onExit cleanup timing on unmount

[angular-bootstrap]

Summary

Fixes a ViewTransition cleanup timing inconsistency for onExit.

Previously, onExit cleanup was attached to transition finish, so it could be delayed even when the transition subtree had already unmounted. This change marks onExit cleanup as unmount-bound and executes it immediately for that path, matching expected unmount cleanup behavior.

Changes

• Extend pending view transition events to carry cleanup behavior metadata.
• Add cleanupOnUnmount support to scheduleViewTransitionEvent.
• Mark onExit scheduling with cleanupOnUnmount: true.
• Execute cleanup immediately for unmount-bound events instead of waiting for transition finish.
• Add regression coverage in ReactDOMViewTransition-test.

Test Plan

• yarn test ReactDOMViewTransition-test --runInBand

Issue

Closes #35855

[react-sizebot]

Comparing: 4cc5b7a...5d7626b

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.js	=	6.84 kB	6.84 kB	+0.05%	1.88 kB	1.88 kB
oss-stable/react-dom/cjs/react-dom-client.production.js	+0.05%	611.79 kB	612.10 kB	+0.06%	108.12 kB	108.18 kB
oss-experimental/react-dom/cjs/react-dom.production.js	=	6.84 kB	6.84 kB	+0.05%	1.88 kB	1.88 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js	+0.09%	677.72 kB	678.36 kB	+0.10%	119.08 kB	119.19 kB
facebook-www/ReactDOM-prod.classic.js	+0.04%	697.72 kB	698.03 kB	+0.05%	122.59 kB	122.65 kB
facebook-www/ReactDOM-prod.modern.js	+0.05%	688.03 kB	688.34 kB	+0.05%	120.97 kB	121.03 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against 5d7626b