Fix @flaky handler to catch subprocess.TimeoutExpired exception. (#25205)

Fix flaky handler to catch subprocess.TimeoutExpired exception. This way
test_main_thread_em_asm_pthread will actually be attempted to be
repeated as flaky.
#25175

E.g. flaky failure at http://clbri.com:8010/api/v2/logs/49999/raw_inline
was not caught and treated as flaky.

Also fixes flaky handling of test_pthread_dlopen_many:
http://clbri.com:8010/api/v2/logs/50283/raw_inline ,
#18887

Author: juj

test/common.py

@@ -246,7 +246,7 @@ def modified(*args, **kwargs):
       for i in range(EMTEST_RETRY_FLAKY):
         try:
           return f(*args, **kwargs)
-        except AssertionError as exc:
+        except (AssertionError, subprocess.TimeoutExpired) as exc:
           preserved_exc = exc
           logging.info(f'Retrying flaky test "{f.__name__}" (attempt {i}/{EMTEST_RETRY_FLAKY} failed): {exc}')
           # Mark down that this was a flaky test.