Add test for order aggs by term #8141

[LeeDr]

Manual backport of #8154 to 4.6.
Added new test to _line_chart.js that changes Order By to Term. It passes on 4.6 branch master with the fix (4.6.1), but fails on 4.6.0 with these messages (I trimmed out some stack trace);

>> FAIL: chrome on any platform - visualize app - visualize app - line charts - should show correct chart order by Term (2772ms)
Error: expected false to be truthy
10:53:29.029: Taking screenshot "C:\git\4.x\test\screenshots\failure\failure_1472831609029_line charts_should show correct data, ordered by Term.png"
>> FAIL: chrome on any platform - visualize app - visualize app - line charts - should show correct data, ordered by Term (935ms)
Error: Error: expected [ 'jpg 9,109',
  'css 2,159',
  'png 1,373',
  'gif 918',
  'php 445' ] to sort of equal [ 'png 1,373',
  'php 445',
  'jpg 9,109',
  'gif 918',
  'css 2,159' ]
10:53:29.399: Start of testLineChartVisualization
10:53:30.455: saveButton button clicked

This line would normally be the successful save notification but shows the error instead;

10:53:30.708: Saved viz message = Visualize: Cannot read property 'type' of undefined

10:53:30.710: Taking screenshot "C:\git\4.x\test\screenshots\failure\failure_1472831610710_line charts_should be able to save and load.png"
>> FAIL: chrome on any platform - visualize app - visualize app - line charts - should be able to save and load (1849ms)

[thomasneirynck]

this is more personal opinion, so whatever you do with this is totally at your discretion.

IMHO, I find the logging statements not necessary. The tests are quite constrained in scope, and a failure should very quickly point to the spot where things go wrong. To me, they help at dev-time, but can be removed once checked in.

[thomasneirynck]

LGTM, only minor comments

[LeeDr]

I eliminated a lot of unused 'remote' vars through the visualize tests.