refactor: replace ext/web timer imports with core timers or node:timers (#33121)
## Summary
- **ext/node polyfills** (`http.ts`, `pipe_wrap.ts`, `_util/async.ts`):
import `setTimeout`/`clearTimeout` from `node:timers` instead of
`ext:deno_web/02_timers.js`
- **ext/websocket** (`01_websocket.js`): use
`core.createTimer`/`core.cancelTimer` directly for idle timeout
management
- **ext/fetch** (`27_eventsource.js`): use
`core.createTimer`/`core.cancelTimer` directly for SSE reconnection
- **runtime** (`99_main.js`): use `core.createTimer` for the exit delay
timer
- Remove unused `webClearTimeout`/`timerId` imports from `http.ts`
- Remove unused `FunctionPrototypeCall` from `99_main.js`
Follow-up to #33118 -- now that Node.js timers are the default, ext/node
polyfills should use them directly, and internal Deno plumbing should
use core timers instead of the web timer wrappers.
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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>