[Bug]: After upgrade from 4.x to 33.0, two instances of dekstop run at the same time and interfere with each other

### ⚠️ 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

After upgrading (and after a reboot), two instances of Desktop were running at the same time, spamming notifications about a folder being modified while it was synched. When I killed one of the two instances, the other one resynched my entire account folder, including some folders that where unchecked from sync. Two instances appeared after every reboot after this.

What I did to fix it is:

1. killed both instances
2. started Desktop from the Cinnamon app menu
3. waited for all the files to be resynched
4. disabled nextcloud desktop from the Cinnamon "Startup applications" menu, which is where Desktop puts itself when you tell it to start at system boot
5. unchecked and checked "start at system boot" option
6. rebooted. Desktop launched itself even if it was disabled in "Startup applications" (has the mechanism to start at boot changed? I don't see any mention to it in the changelogs)

### Steps to reproduce

1. Upgrade from 4.x to 33.0. 4.x client must be configured to start at system boot
2. Wait

### Expected behavior

Two instances should not run, and even if they did, it should not cause the entire folder to be resynched.

### Which files are affected by this bug

"Create debug archive" button is disabled, so I cannot generate any log

### Operating system

Linux

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

Linux Mint 22.3 Cinnamon

### Package

Official PPA

### Nextcloud Server version

31.0.13

### Nextcloud Desktop Client version

33.0.0daily

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

Updated to a major version (ex. 3.16.3 to 3.17.0)

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

Encryption is Disabled

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

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

### Nextcloud Server logs

```shell

```

### Additional info

_No response_