Change: use spaces instead of hsep in timetable GUI

[WenSimEHRP]

Motivation / Problem

The time bar in the timetable window uses an hsep_wide to seperate the arrival/departure abbreviations and the time. This does not work well with languages that use the ideographic colon, or the fullwidth colon, as the gap is now super wide.

zh_CN (fullwidth colon)	zh_TW (fullwidth colon)	en (halfwidth colon)

Description

Remove the hsep and add two {SPACE} after the abbreviation. It seems like that these strings are only used in the timetables window.

zh_TW (fullwidth colon)	en (halfwidth colon + 2x {SPACE})

Limitations

• I didn't change other language's translation.
• Might break text alignment??

Checklist for review

Some things are not automated, and forgotten often. This list is a reminder for the reviewers.

• The bug fix is important enough to be backported? (label: 'backport requested')
• This PR touches english.txt or translations? Check the [guidelines](https://github.com/OpenTTD/OpenTTD/blob/master/docs/eints.md)
• This PR affects the save game format? (label 'savegame upgrade')
• This PR affects the GS/AI API? (label 'needs review: Script API')
  • ai_changelog.hpp, game_changelog.hpp need updating.
  • The compatibility wrappers (compat_*.nut) need updating.
• This PR affects the NewGRF API? (label 'needs review: NewGRF')
  • newgrf_debug_data.h may need updating.
  • PR must be added to API tracker

[JGRennison]

Seems OK, I will fix the other languages in a separate commit