fix user search problem happening after user deletion

[karakayasemi]

Backport of owncloud/core#36431

[CLAassistant]

All committers have signed the CLA.

[karakayasemi]

Some of the unit tests unrelated to this change failed. Looks like Dependabot update PRs also failed in the same tests. If we want to keep maintaining this repo, we need to have a look at them.

[phil-davis]

IMO this repo is unmaintained. I fully expect that "recent" drone CI environment changes will mean that a bunch of stuff "just does not work". Nobody has kept code up-to-date here sinces the core stable10 => master branch change.
@micbar @PVince81 @DeepDiver1975 comments?

[phil-davis]

@micbar ping again.
What is the required status for this repo?
Archive? Or get the code and CI up-to-date?

[micbar]

We abandon this repo.