[v12.0/forgejo] fix: make the action feed resilient to database inconsistencies (#8618)

**Backport:** https://codeberg.org/forgejo/forgejo/pulls/8617

This reverts commit 7380eac5a2.

Resolves forgejo/forgejo#8612

It is possible for the action feed to reference deleted repositories the
`INNER JOIN` will make sure that these are filtered out. We cannot
filter these out after the fact, because the value of `count` will still
be incorrect.

<!--start release-notes-assistant-->

## Release notes
<!--URL:https://codeberg.org/forgejo/forgejo-->
- Bug fixes
  - [PR](https://codeberg.org/forgejo/forgejo/pulls/8617): <!--number 8617 --><!--line 0 --><!--description bWFrZSB0aGUgYWN0aW9uIGZlZWQgcmVzaWxpZW50IHRvIGRhdGFiYXNlIGluY29uc2lzdGVuY2llcw==-->make the action feed resilient to database inconsistencies<!--description-->
<!--end release-notes-assistant-->

Co-authored-by: Gusted <postmaster@gusted.xyz>
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8618
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: forgejo-backport-action <forgejo-backport-action@noreply.codeberg.org>
Co-committed-by: forgejo-backport-action <forgejo-backport-action@noreply.codeberg.org>

models/activities/action_test.go

@@ -227,6 +227,24 @@ func TestNotifyWatchers(t *testing.T) {
 	})
 }
 
+func TestGetFeedsCorrupted(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+	user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+	unittest.AssertExistsAndLoadBean(t, &activities_model.Action{
+		ID:     8,
+		RepoID: 1700,
+	})
+
+	actions, count, err := activities_model.GetFeeds(db.DefaultContext, activities_model.GetFeedsOptions{
+		RequestedUser:  user,
+		Actor:          user,
+		IncludePrivate: true,
+	})
+	require.NoError(t, err)
+	assert.Empty(t, actions)
+	assert.Equal(t, int64(0), count)
+}
+
 func TestConsistencyUpdateAction(t *testing.T) {
 	if !setting.Database.Type.IsSQLite3() {
 		t.Skip("Test is only for SQLite database.")