feat(next-swc): force teardown heap profiler if exists (#47769)

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### What?

This is followup for #47729, for
some cases (mostly test) it forces child process so normal teardown to
flush may not being called. PR enables force flushing for those process
event. Same as original changes, for the normal next-swc this won't
affect anything.

Author: kwonoj

packages/next/src/cli/next-dev.ts

@@ -219,7 +219,7 @@ const nextDev: CliCommand = async (argv) => {
 
     const { validateTurboNextConfig } =
       require('../lib/turbopack-warning') as typeof import('../lib/turbopack-warning')
-    const { loadBindings, __isCustomTurbopackBinary } =
+    const { loadBindings, __isCustomTurbopackBinary, teardownHeapProfiler } =
       require('../build/swc') as typeof import('../build/swc')
     const { eventCliSession } =
       require('../telemetry/events/version') as typeof import('../telemetry/events/version')
@@ -286,6 +286,13 @@ const nextDev: CliCommand = async (argv) => {
     if (!isCustomTurbopack) {
       await telemetry.flush()
     }
+
+    // There are some cases like test fixtures teardown that normal flush won't hit.
+    // Force flush those on those case, but don't wait for it.
+    ;['SIGTERM', 'SIGINT', 'beforeExit', 'exit'].forEach((event) =>
+      process.on(event, () => teardownHeapProfiler())
+    )
+
     return server
   } else {
     let cleanupFns: (() => Promise<void> | void)[] = []