Remove functest_testsuite and functest_testcase in dovetail_config.yml

Remove functest_testsuite and functest_testcase in dovetail_config.yml

The 2 sections 'functest_testsuite' and 'functest_testcase' are used by
all Functest test cases.

They aim to parse the results of Tempest sub test cases.

Remove them, and check the sub test case list,
1. if it's empty, that means no need to check sub test cases
2. if it is not empty, check the sub test cases one by one.

Additional, remove some useless keys in dovetail_config.yml

JIRA: DOVETAIL-658

Change-Id: Ic829264b0c8eaedd8e2b3fa55b38a34644482c20
Signed-off-by: xudan <xudan16@huawei.com>