testsuitegenerator: Change values tested for 'flags' config options
testsuitegenerator: Change values tested for 'flags' config options

Test both 'constructive' and 'primary' to better verify that correct
icon variants are chosen in MediaWiki theme.

This exposed an issue where a button with { framed: false, flags: 'primary' }
would have a different-colored icon in PHP and JS, fixed in
Ibb8db8af965b9fbf5bc7af6b6f8dc4c552daa662.

Change-Id: I353791f7398d9f6f74a255345d5ce4ae220c72b3

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui