searchSatisfaction: Don't bind high-level delegated event handler
I2710b28e introduced a performance regression by attaching a delegated
event handler to the body element that would require at least running a
jQuery Selector once whenever an input, change, paste, or keypress event
was emitted for any element on the page.
Following Krinkle's advice in T274869#6902338, bind the delegated event
handler to #p-search or #searchText elements, which are container
elements for search boxes on all pages (the latter is the container
element for the search box on Special:Search).