Gitlab 110 - Ensure tests better asses if desired outcome has been reached

[shayfaber]

Changes

• Most tests now have an additional check to ensure the desired outcome has actually been reached (or not!)
• expects that asses if a notification is shown are now so called soft expects: the test will continue but mark the test. This is to ensure the additional check can still run.
• Known issue for Firefox: The minicart button in the menu does not lose the "aria-disabled=true" flag when the first product is added to the cart, even after reload() and waitFor(). This prevents Playwright from opening the minicart and therefore continuing the test. Only consistently happens in UI mode, only when the first product gets added. Sometimes succeeds and sometimes fails when run from the terminal.

[dheesen]

@shayfaber Tiny remark of, I think, missed soft expect.