Remove outdated unused jquery.tipsy styles from common/shared.css

Remove outdated unused jquery.tipsy styles from common/shared.css

This code is really, really old and not compatible with jquery.tipsy
anymore. Look at the image. It's a single arrow. That's not how
the tipsy version we are currently using works. It needs to be a
star with arrows pointing to all four directions.

Luckily this is just dead code. The jquery.tipsy.css file is loaded
after shared.css and overrides the outdated styles anyway.

Wikibase uses it's own styles for the tipsy tooltips. So there are
three places that try to style the tipsy tooltips: shared.css,
tipsy.css and Wikibase' wbtooltip.css. For some reason this broke
the ULS tooltips on wikidata.org. I would like to fix this mess by
removing all individual styles. I will submit an other patch that
removes the individual styles in Wikibase.

Bug: 67802
Change-Id: Idfd3a5e30dd2f24dbd588a30c1f516d5d219ced5