Add test cases for order by last modified time and score

[otegami]

close: https://github.com/clear-code/redmine_full_text_search/issues/120

What I did

• Added test cases for order by last modified time and score

What I checked

• I checked test cases passed

[otegami]

@kou Could you review it when you have time?🙏

[otegami]

@kou Thank you for the reviews. I've just fixed what you pointed out.

[otegami]

@kou Thank you for the reviews. I've just fixed what you pointed out.

[kou]

Thanks!