fix: only track block effects when deferred to prevent infinite HMR infinite loops

[hmnd]

fixes #17369

Caused by #17332. Block effects were added to dirty_effects unconditionally even if they run immediately. Then on HMR, revive kept rescheduling them causing an infinite, memory eating loop.

Unsure how best to test this one though...

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Playground

pnpm add https://pkg.pr.new/svelte@17374