[api_fuzzer] Attempt to clean up fuzzer memory leak (#33120)

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test/core/end2end/fuzzers/api_fuzzer.cc

@@ -847,6 +847,8 @@ ApiFuzzer::~ApiFuzzer() {
   GPR_ASSERT(ActiveCall() == nullptr);
   GPR_ASSERT(calls_.empty());
 
+  engine_->TickUntilIdle();
+
   grpc_completion_queue_shutdown(cq_);
   GPR_ASSERT(PollCq() == Result::kComplete);
   grpc_completion_queue_destroy(cq_);

test/core/end2end/fuzzers/api_fuzzer_corpus/clusterfuzz-testcase-minimized-api_fuzzer-4996188645228544

@@ -0,0 +1,13 @@
+actions {
+  create_channel {
+    target: "1"
+    channel_actions {
+    }
+  }
+}
+actions {
+  check_connectivity: true
+}
+actions {
+  disable_tracer: "1"
+}

test/core/end2end/fuzzers/api_fuzzer_corpus/clusterfuzz-testcase-minimized-api_fuzzer-5393262423965696.test

@@ -0,0 +1,27 @@
+actions {
+  create_channel {
+    target: "unix::p<,0,,, 140J"
+    channel_actions {
+    }
+  }
+}
+actions {
+  check_connectivity: true
+}
+actions {
+  enable_tracer: "V)"
+}
+actions {
+  poll_cq {
+  }
+}
+actions {
+  close_channel {
+  }
+}
+event_engine_actions {
+  tick_lengths {
+    id: 4
+    delay_us: 409823569256
+  }
+}