Wrong timezone detection (always UTC)

[Skia]

With tzdata 2024b-1ubuntu1 (plucky-proposed), the timezone is wrongly detected to be UTC, no matter what I do.

This is working fine with 2024a-4ubuntu1, which is what was released in Oracular.

Simple reproducer:
```cpp
#include <chrono>
#include <iostream>

int main() {
    const std::chrono::zoned_time cur_time{ std::chrono::current_zone(),
                                            std::chrono::system_clock::now() };
    std::cout << cur_time << '\n';
}
```
Compiled with `g++ -std=c++20 main.cpp`

```
$ ./a.out
2024-10-21 16:14:17.489489001 UTC
$ dpkg-query -W tzdata
tzdata 2024b-1ubuntu1
$ sudo apt install tzdata/oracular
[...]
$ dpkg-query -W tzdata
tzdata 2024a-4ubuntu1
$ ./a.out
2024-10-21 18:16:25.554620585 CEST
```

ProblemType: Bug
DistroRelease: Ubuntu 25.04
Package: tzdata 2024b-1ubuntu1
ProcVersionSignature: Ubuntu 6.8.0-45.45-generic 6.8.12
Uname: Linux 6.8.0-45-generic x86_64
NonfreeKernelModules: zfs
ApportVersion: 2.30.0-0ubuntu4
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: sway
Date: Mon Oct 21 14:11:36 2024
InstallationDate: Installed on 2023-08-02 (446 days ago)
InstallationMedia: Ubuntu 23.04 "Lunar Lobster" - Release amd64 (20230418)
PackageArchitecture: all
ProcEnviron:
 LANG=fr_FR.UTF-8
 PATH=(custom, no user)
 SHELL=/bin/zsh
 TERM=alacritty
 XDG_RUNTIME_DIR=<set>
SourcePackage: tzdata
UpgradeStatus: Upgraded to plucky on 2024-06-12 (131 days ago)

[Skia (hyask)]

Funny `UpgradeStatus: Upgraded to plucky on 2024-06-12 (131 days ago)`, btw, but this is unrelated. :-)

[Benjamin Drung (bdrung)]

I can reproduce the failure on Ubuntu, but it works on Debian unstable:

```
# dpkg -s tzdata | grep ^Version
Version: 2024b-3
# dpkg-reconfigure tzdata
[...]
Current default time zone: 'Europe/Berlin'
Local time is now: Wed Oct 23 10:47:35 CEST 2024.
Universal Time is now: Wed Oct 23 08:47:35 UTC 2024.

# ls /etc/localtime -l
lrwxrwxrwx 1 root root 33 Oct 23 10:47 /etc/localtime -> /usr/share/zoneinfo/Europe/Berlin
# ./a.out
2024-10-23 10:52:41.398553339 CEST
```