util-date: cleanup to use %X instead of manually determining user's time

The code have been asking config whether the user has 12 or 24 time
format, and then used that for prints. As far as I can see config gets
the value from environment.

In addition, there was a bug: LOCALE_DEFAULT time format used "%l:%M %P"
which is always AM/PM, even though the comment said that the time should
be locale default here.

Let's remove all that complexity, and use the %X specifier directly
which gives time in a locale preferred format.

Signed-off-by: Konstantin Kharlamov <Hi-Angel@yandex.ru>
6 jobs for cleanup-time-formatting in 14 minutes and 53 seconds
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00:03:49

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ubuntu

00:06:17

 
  Test
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deb-package

00:08:34

failed #226587
flatpak

00:06:02

 
  Deploy
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review
skipped #226589
allowed to fail manual
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Name Stage Failure
failed
flatpak Test

Full log written to /builds/Hi-Angel/geary/_build/meson-logs/testlog.txt
A connection to the bus can't be made
Uploading artifacts...
WARNING: geary-dev.flatpak: no matching files
_build/meson-logs/meson-log.txt: found 1 matching files
_build/meson-logs/testlog.txt: found 1 matching files
Uploading artifacts to coordinator... ok id=226587 responseStatus=201 Created token=6Nnrb61q
ERROR: Job failed: exit code 1