numerous icon tests expect the actual production plasma theme to be present
it won't however be resolved because we disable qstandardpaths' default
fallbacks by switching it into testing mode. this ultimately means the
test run needs to have XDG_DATA_DIRS in the environment, if it doesn't
test data will not be present
furthermore QSKIP tests that depend on:
- hicolor icon theme to be present
- production plasma themes
this allows the entire test to pass in less than optimal environments by
means of skipping but also gives a reasonable hint as to why tests are
skipped in the first place. also moving forward if a test isn't guarded
we still have the warning about failure potential allowing someone to
quickly figure out why things failed
REVIEW: 127764
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