[ISSUE] Lightdm Ignores Limit Values

[TrueTechie <TrueTechie@users.noreply.github.com>]

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New issue by TrueTechie on void-packages repository

https://github.com/void-linux/void-packages/issues/40305

Description:
### Is this a new report?

Yes

### System Info

Void 5.19.17_1 x86_64 GenuineIntel uptodate FFFFF

### Package(s) Affected

pam-1.5.2_2 lightdm-1.32.0_2

### Does a report exist for this bug with the project's home (upstream) and/or another distro?

_No response_

### Expected behaviour

After setting up Lightdm and modifying `/etc/security/limits.conf` and restarting the system, the output of `ulimit -Hn` should be the same as that defined in the configuration file. 

For example, mine has the following line for playing games with ESync:
```
elliot hard nofile 524288
```
So the output of `ulimit -Hn` would be: `524288`

### Actual behaviour

No matter what is written in `/etc/security/limits.conf`, the output of `ulimit -Hn` is just the default of `4096`. According to [this issue](https://github.com/void-linux/void-packages/issues/20105) in 2020, this can be fixed by adding `session required pam_limits.so` to `/etc/pam.d/lightdm`. This should be enabled by default, but the issue was automatically closed due to inactivity.

### Steps to reproduce

1. Install and configure Lightdm
2. Set limits in `/etc/security/limits.conf`
3. Restart system
4. Log in via Lightdm
5. Run `ulimit -Hn`