Fix art-debug-gc tests

It is expected that the trace file might be sometimes missing.

Test: ./art/test/testrunner/run_build_test_target.py -j80 art-debug-gc
Change-Id: I2285da2d73a5c05695b92621c08557e1a38a84ed
diff --git a/test/run-test b/test/run-test
index db0885e..c59a4e3 100755
--- a/test/run-test
+++ b/test/run-test
@@ -977,7 +977,8 @@
                  f'"{ctx.expected_stderr}" "{test_stderr}"', check=False)
   if strace == "yes":
     print("#################### strace output (trimmed to 3000 lines)")
-    run(f'tail -n 3000 "{tmp_dir}/{strace_output}"')
+    # Some tests do not run dalvikvm, in which case the trace does not exist.
+    run(f'tail -n 3000 "{tmp_dir}/{strace_output}"', check=False)
   SANITIZE_HOST = os.environ.get("SANITIZE_HOST")
   if target_mode == "no" and SANITIZE_HOST == "address":
     # Run the stack script to symbolize any ASAN aborts on the host for SANITIZE_HOST. The