Tooltip directive should set aria-label by default

Assigning both the same title and aria-label seems a bit noisy. Should we just use the title as an aria-label as default?

      v-gl-tooltip
      :aria-label="s__('Security Reports|Create issue')"
      :title="s__('Security Reports|Create issue')"

could be

      v-gl-tooltip
      :title="s__('Security Reports|Create issue')"

Maybe we also could go with aria-describedby, this is what Bootstrap 3 did 🤔

Example from here