testimage.bbclass: also check 'auto' to create rpm index
Having 'auto' in TEST_SUITES will also run the 'dnf' test cases,
so also check it to determine whether to create rpm index or not.
This is to fix the following error when TEST_SUITES = "auto".
RESULTS - dnf.DnfRepoTest.test_dnf_makecache - Testcase 1744: ERROR
(From OE-Core rev:
c1f4177848d25a9121f2a85da655ee414cd424b1)
Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>
