[Bug]: Directory is already being used as a sync folder.

### ⚠️ Before submitting, please verify the following: ⚠️

- [x] This is a **bug**, not a question or a configuration issue.
- [x] This issue is **not** already reported on Github (I've searched it).
- [x] Nextcloud Server and Desktop Client are **up to date**. See [Server Maintenance and Release Schedule](https://github.com/nextcloud/server/wiki/Maintenance-and-Release-Schedule) and [Desktop Releases](https://nextcloud.com/install/#install-clients) for supported versions.
- [x] I agree to follow Nextcloud's [Code of Conduct](https://nextcloud.com/contribute/code-of-conduct/)

### Bug description

I cannot add a directory for syncing after removing it.

### Steps to reproduce

1. Open Settings -> Standard file sync
2. Add folder sync connection
3. choose a directory
4. let it sync
5. remove the directory
6. try to add it again


### Expected behavior

The directory should be synced.

### Which files are affected by this bug

N/A

### Operating system

Linux

### Which version of the operating system you are running.

Arch Linux + GNOME 47

### Package

Official Linux AppImage

### Nextcloud Server version

30.0.4

### Nextcloud Desktop Client version

3.16.0

### Is this bug present after an update or on a fresh install?

Fresh desktop client install

### Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

### Are you using an external user-backend?

- [x] Default internal user-backend
- [ ] LDAP/ Active Directory
- [ ] SSO - SAML
- [ ] Other

### Nextcloud Server logs

```shell

```

### Additional info

_No response_