[autotest] Parse RETRIES from control files

Parse the RETRIES variable from control files and insert into job/test
databased entry. This happens in suite.py before creation of suite sub-jobs,
and in test_importer when importing new tests into afe_autotests database.

Ran utils/test_importer.py and verified that 2 tests name
flaky_test both had test_retry imported correctly with value 2 (in
afe_autotests table).
Kicked off a dummyflake suite and verified that its sub jobs were
created with test_retry=2.

Change-Id: I93eb0f4581120082a82c46b2be98286ede248c94
Reviewed-on: https://gerrit.chromium.org/gerrit/44435
Tested-by: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: Alex Miller <milleral@chromium.org>
Commit-Queue: Scott Zawalski <scottz@chromium.org>
Reviewed-by: Scott Zawalski <scottz@chromium.org>
Tested-by: Scott Zawalski <scottz@chromium.org>
5 files changed