Bug 1085667 - [Music] Try clicking on share button mutliple times

https://bugzilla.mozilla.org/show_bug.cgi?id=1085667

TC run: https://treeherder.allizom.org/ui/#/jobs?repo=gaia&revision=0eb07a8532d0eaaa063ffe224b35e2dd05c62055

Another TC run: https://treeherder.allizom.org/ui/#/jobs?repo=gaia&revision=89ba86a25d60d17032bcfc5c7c3e46f15823a803
It just needs to be fast enough to trigger before the menu button visibility changes. 50ms is generally what we use in other contexts where we need a 'fast client'. Otherwise what might happen is that the test could timeout if we don't fail fast enough (the share button disappears).