fix(watch): avoid pre watcher firing on unmount

fix #12703

Author: yyx990803

src/v3/apiWatch.ts

@@ -274,10 +274,7 @@ function doWatch(
   let oldValue = isMultiSource ? [] : INITIAL_WATCHER_VALUE
   // overwrite default run
   watcher.run = () => {
-    if (
-      !watcher.active &&
-      !(flush === 'pre' && instance && instance._isBeingDestroyed)
-    ) {
+    if (!watcher.active) {
       return
     }
     if (cb) {

test/unit/features/v3/apiWatch.spec.ts

@@ -542,7 +542,7 @@ describe('api: watch', () => {
     expect(cb).not.toHaveBeenCalled()
   })
 
-  it('should fire on component unmount w/ flush: pre', async () => {
+  it('should not fire on component unmount w/ flush: pre', async () => {
     const toggle = ref(true)
     const cb = vi.fn()
     const Comp = {
@@ -560,7 +560,7 @@ describe('api: watch', () => {
     expect(cb).not.toHaveBeenCalled()
     toggle.value = false
     await nextTick()
-    expect(cb).toHaveBeenCalledTimes(1)
+    expect(cb).not.toHaveBeenCalled()
   })
 
   // vuejs/core#1763