fixes missing imege url errors in logo component tests

Initially I used some arbitrary strings for big / small logo URLs in my fixtures. Because template is appended to the DOM during tests, this results in missing image errors polluting browser's console. I've checked only that tests pass, didn't think about checking also console output.

I have fixed fixture to use paths to existing images instead of arbitrary ones.

Sorry for not checking console output and missing this when verifying original PR!