To achive this the `stream_header_colorblock` div was removed from
`dropdown_widget_with_stream_colorblock.hbs` template. this change made
the file name irelevenet so it was necessary to rename the file to
`dropdown_widget_wrapper.hbs`. After removing the html strcuture for
colorblock from templates the css for colorblock was also removed.
followed by the javascript which was used to add colorblock to the
stream picker. After removing javascript tests were updated.
Fixes: #28796.
Mahhheshh