Amends a452e22546. No new tests, existing
tests fails when QPlatformTheme returns a QIconEngine implementation
that provides the tested icons. However, the existing test fails when
the platform icon engine provides and address-book-new icon, and depends
on the order of test functions, as the name() test function modifies the
global theme name and search path. Fix those issues in the test.
Pick-to: 6.6
Change-Id: Ie1c1d14f08fad5e906296bab662df5cfacdbbf07
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>