Revert "date: Replace U+2009 THIN SPACE in formatted dates with U+0020 SPACE"

This reverts commit 57fc066e68f55ef408ee91d2023380fd49f2dec3.

Reason for revert: Suspected to break date-sensitive browser tests
in roll:
https://ci.chromium.org/ui/p/chromium/builders/try/linux-rel/2598830/overview

Original change's description:
> date: Replace U+2009 THIN SPACE in formatted dates with U+0020 SPACE
>
> Recent ICU updates introduced non-ASCII space characters in formatted
> date/time strings. This can cause compatibility problems for systems
> that parse or display this output and expect standard ASCII spaces.
>
> To ensure broader compatibility, this change replaces these newer
> Unicode spaces with the ASCII space character (U+0020), an approach also
> taken by Firefox [1].
>
> This CL addresses two recent changes in ICU:
> * ICU 78 began using U+2009 in date/time format for "zh" locales.
> * ICU 72 began using U+2009 in date/time ranges format for "en" locales.
>
> This change builds upon a previous fix for U+202F (NARROW NO-BREAK
> SPACE). The `Replace202F` function is renamed to `ReplaceUnicodeSpaces`
> and is updated to replace both U+2009 and U+202F.
>
> [1]
> https://github.com/mozilla-firefox/firefox/blob/main/intl/components/src/DateTimeFormat.h#L39
>
> Bug: 473861785
> Change-Id: I72e0cce5e6e72917d874d59c43d7768a6f1c86b5
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/7652321
> Commit-Queue: Marja Hölttä <marja@chromium.org>
> Auto-Submit: Kent Tamura <tkent@chromium.org>
> Reviewed-by: Frank Tang <ftang@chromium.org>
> Reviewed-by: Marja Hölttä <marja@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#105796}

Bug: 473861785
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: Ica10501f05e11ab9eaa5d497808371cdd4a2cdd3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/7669037
Auto-Submit: Michael Achenbach <machenbach@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#105799}