Fix setFindTimeout defaults to 10 seconds.

[LeeDr]

We've been using the same default timeout of 90 seconds (in intern.js) for both how long a test can run, and for how long we try to find an element on the page. This is bad because when we fail to find an element on a page we will always hit the test timeout first, and then we don't get any logging about what element we failed to find.

This change adds a findTimeout of 10 seconds to intern.js and changes all the support/page/*page.js files to use this new findTimeout.

Finally, in settings_page.js, in setAdvancedSettings there was a place that I added an explicit setFindTimeout.

[w33ble]

kibana/test/support/pages/shield_page.js is still using the defaultTimeout, and should also be changed to the findTimeout. Make that one change, and this LGTM.