Remove untranslatable on_date key (#24106)

- Follows #23988 
- Fixes: #24074 by removing this key

GitHub's `relative-time` elements allow us to force their rendering to
`auto`, `past`, or `future` tense. We will never show an absolute date
`on ...` in `TimeSince`

## Before

![image](https://user-images.githubusercontent.com/20454870/231735872-048c7bf3-6aa1-4113-929d-75a985c9922c.png)

## After

![image](https://user-images.githubusercontent.com/20454870/231736116-6ad47b63-77f4-4d3f-82a2-ee9a46ba2bd1.png)

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

options/locale/locale_en-US.ini

@@ -112,8 +112,6 @@ never = Never
 
 rss_feed = RSS Feed
 
-on_date = on
-
 [aria]
 navbar = Navigation Bar
 footer = Footer
@@ -3129,8 +3127,6 @@ starred_repo = starred <a href="%[1]s">%[2]s</a>
 watched_repo = started watching <a href="%[1]s">%[2]s</a>
 
 [tool]
-ago = %s ago
-from_now = %s from now
 now = now
 future = future
 1s = 1 second