Bump leak_tracker to 3d4c0d6db7d56af5fe52d6729ef373a3ec4de65b

Changes:
```
> git log --format="%C(auto) %h %s" 8644f8b..3d4c0d6
 https://dart.googlesource.com/leak_tracker.git/+/3d4c0d6 Fix `labeler.yml` (202)
 https://dart.googlesource.com/leak_tracker.git/+/4efea69 Bump actions/labeler from 4.3.0 to 5.0.0 (200)
 https://dart.googlesource.com/leak_tracker.git/+/e52329c Add global enabler to LeakTesting. (197)
 https://dart.googlesource.com/leak_tracker.git/+/c71a905 Standardize lints to dart_flutter_team_lints (198)
 https://dart.googlesource.com/leak_tracker.git/+/8393a23 Cleanup leak_tracker. (195)
 https://dart.googlesource.com/leak_tracker.git/+/f88cb6a Remove declaration of testWidgetsWithLeakTracking. (194)
 https://dart.googlesource.com/leak_tracker.git/+/f361ed8 Update `vm_service` dependency to `>=11.0.0 <15.0.0` (193)
 https://dart.googlesource.com/leak_tracker.git/+/106bd2b Add API to integrate with testWidgets. (188)
 https://dart.googlesource.com/leak_tracker.git/+/a9966d2 Increase delay to fix flakiness of integration test related to memory snapshotting. (191)

```

Diff: https://dart.googlesource.com/leak_tracker.git/+/8644f8b1c78009e9149e08e0c349d06c304110a9..3d4c0d6db7d56af5fe52d6729ef373a3ec4de65b/
Change-Id: Iddb323c4c45062393ccb170f01a03b48742d4280
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/344541
Reviewed-by: Polina Cherkasova <[email protected]>
Auto-Submit: Devon Carew <[email protected]>
Commit-Queue: Polina Cherkasova <[email protected]>

Author: devoncarew

DEPS

@@ -154,7 +154,7 @@ vars = {
   "http_parser_rev": "224c1a9d24b46c7a9da1f09147e0e1fbda78089d",
   "intl_rev": "5d65e3808ce40e6282e40881492607df4e35669f",
   "json_rpc_2_rev": "ac1fabddd51fc90aa6fa4e1248f1a7141899eb4a",
-  "leak_tracker_rev": "8644f8b1c78009e9149e08e0c349d06c304110a9",
+  "leak_tracker_rev": "3d4c0d6db7d56af5fe52d6729ef373a3ec4de65b",
   "lints_rev": "3810f8b3dc3205cfaa4ccc0054b021e68046d851",
   "logging_rev": "4d35a4e02b9237bd794378413e7ce3deb52ffcaf",
   "markdown_rev": "d2e790305d136b4eb39d329c884bb49d5a5f1411",