To extract commments for translators, '--add-comments' option
must be passed to pybabel. Comments for translators were extracted
when we used Django tools to extract messages, but when we switched
to pybabel it was lost. This commit adds the option to run_tests.sh.
Move the place of existing comments for translators
so that pybabel can find them. Django tool and pybabel
expect a bit different places.
Also add comments to ungettext_lazy in test codes.
Closes-Bug: #1553581
Change-Id: Ia2df36dfebb59bede19d57b2158a907126ca1944