[testing] Skip slow test on AOT/debug with null-safety enabled

This test takes 16 to 32mins on bots before timing out without producing
a result.

Possibly related issue:
https://github.com/dart-lang/sdk/issues/43614

Change-Id: Ic0bf79e6d1b5276c7dae99b7c8f719e0f706e1a4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/166000
Reviewed-by: Karl Klose <karlklose@google.com>
diff --git a/tests/co19/co19-runtime.status b/tests/co19/co19-runtime.status
index f34b3eb..0a91266 100644
--- a/tests/co19/co19-runtime.status
+++ b/tests/co19/co19-runtime.status
@@ -12,5 +12,8 @@
 [ $compiler != dart2js && $runtime != none && $runtime != vm && !$checked ]
 LibTest/async/Future/catchError_A03_t05: RuntimeError
 
+[ $mode == debug && $nnbd != legacy && $runtime == dart_precompiled ]
+LibTest/collection/ListMixin/ListMixin_class_A01_t05: SkipSlow # Issue 43614
+
 [ $compiler == fasta || $runtime == dart_precompiled || $runtime == vm ]
 LibTest/html/*: SkipByDesign # dart:html not supported on VM.