nextuid get reset after importing from a backup

[K3rN3lPaN1c]

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• I have read the contributing guide lines at https://github.com/opnsense/core/blob/master/CONTRIBUTING.md
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Describe the bug

When we import a config backup from one opnsense to an another one including users the nextuid was ignored on 2 machines. So after adding new user on the web ui the uid was (re)starting from the initial 2000 causing uid collision (2 users had the same uid)

To Reproduce

Steps to reproduce the behavior:

1. Create a config backup on opnsense-01
2. Import the backup on opnsense-02
3. Check the created users (Lookong good)
4. Create a new user on opnsense-02
5. The new user have the initial UID of 2000

Expected behavior

When importing a config backup it should respect the nextuid parameter and should not restart the UID creation.

Environment

Software version used and hardware type if relevant, e.g.:

OPNsense 24.1.5_3-amd64.
Intel Xeon Processor (Skylake, IBRS) (4 cores, 8 threads)

[fichtner]

Step 1: unclear WRT relevant contents of config.xml
Step 3: Unclear where a user was created that was "ok" (what does "ok" mean?)