Remove usages of `data-original-title`

This attribute gets created and updated automatically by Bootstrap's tooltip JS; we should never be assigning to or reading from it.

$ git grep original-title
app/assets/javascripts/awards_handler.coffee:    if $(that).siblings("button:has([data-emoji=#{emoji}])").attr("data-original-title")
app/assets/javascripts/awards_handler.coffee:      $(that).siblings("button:has([data-emoji=#{emoji}])").attr("data-original-title").indexOf('me') > -1
app/assets/javascripts/awards_handler.coffee:      .attr("data-original-title")
app/assets/javascripts/awards_handler.coffee:      .attr("data-original-title", authors.join(", "))
app/assets/javascripts/awards_handler.coffee:    origTitle = award_block.attr("data-original-title").trim()
app/assets/javascripts/awards_handler.coffee:    award_block.attr("data-original-title", authors.join(", "))
app/assets/javascripts/awards_handler.coffee:      "<button class='btn award-control js-emoji-btn has-tooltip active' data-original-title='me'>",
features/steps/project/issues/award_emoji.rb:      expect(page).to have_css(".js-emoji-btn.active[data-original-title='me']")

cc @vsizov