tests: Speedup tests by 30%.

Baseline:
  2598325153 function calls (2598296959 primitive calls) in 2257.698 seconds

Post-changeset:
 1495427 function calls (1467233 primitive calls) in 1572.080 seconds

Change-Id: I191b68b29c9e0f19964bf0b8879ddf357c9cbd5c
Signed-off-by: Paul Vinciguerra <pvinci@vinciconsulting.com>

test/run_tests.py

@@ -441,6 +441,7 @@ def run_forked(testcase_suites):
                                                    manager)
                     wrapped_testcase_suites.add(new_testcase)
                     unread_testcases.add(new_testcase)
+            time.sleep(0.1)
     except Exception:
         for wrapped_testcase_suite in wrapped_testcase_suites:
             wrapped_testcase_suite.child.terminate()