Update scrollspy.js

Scrollspy target in tab content does not work properly. Calling .parents('.active') will return all parents with an active class (including the tab pane). Changing this line to .parentsUntil(this.options.target, '.active') should resolve the issue. This will scope the query to only search for active elements inside the scrollspy target.
Added unit test for removing only active class from within the scroll spy key.
Merge pull request #11453 from moodyroto/patch-1

fix scrollspy for targets within tabs