Fix LDAP Background Sync does not reset offset

[blizzz]

As observed on our instance… issue was that it was reported that more results are expected, while the count was already below the requested limit.

[codecov]

Codecov Report

Merging #7713 into master will increase coverage by 0.05%.
The diff coverage is 24.39%.

@@             Coverage Diff              @@
##             master    #7713      +/-   ##
============================================
+ Coverage     51.18%   51.23%   +0.05%     
- Complexity    24948    24954       +6     
============================================
  Files          1605     1607       +2     
  Lines         94923    94957      +34     
  Branches       1376     1376              
============================================
+ Hits          48583    48652      +69     
+ Misses        46340    46305      -35

Impacted Files	Coverage Δ	Complexity Δ
...ps/user_ldap/composer/composer/autoload_static.php	0% <ø> (ø)	1 <0> (ø)	⬇️
apps/user_ldap/lib/ConnectionFactory.php	0% <0%> (ø)	2 <2> (?)
apps/user_ldap/lib/AccessFactory.php	0% <0%> (ø)	2 <2> (?)
.../user_ldap/composer/composer/autoload_classmap.php	0% <0%> (ø)	0 <0> (ø)	⬇️
apps/user_ldap/lib/Jobs/Sync.php	64% <52.63%> (+37.61%)	46 <9> (+2)	⬆️

[blizzz]

I added several more tests, and fixed one issue with that.

On our instance I see that the offset is not being reset, this should have been fixed though, but isn't. New addition is about rotating the prefix which does not apply to us.