Fix show results for multiple groups in /test/overview

[okurz]

When the query has different groupid and every group
different builds the current operation only returns the jobs
for the last build of the first group.

This PR ensures to return all the jobs for all the last builds for
all the selected groups

https://progress.opensuse.org/issues/91650

Supersedes #3971

[codecov]

Codecov Report

Merging #3973 (ffc1376) into master (02699d6) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #3973   +/-   ##
=======================================
  Coverage   96.86%   96.87%           
=======================================
  Files         370      370           
  Lines       32966    32980   +14     
=======================================
+ Hits        31934    31949   +15     
+ Misses       1032     1031    -1     

Impacted Files	Coverage Δ
lib/OpenQA/WebAPI/Controller/Test.pm	93.76% <100.00%> (+0.01%)	⬆️
lib/OpenQA/WebAPI/Plugin/Helpers.pm	94.09% <100.00%> (+0.12%)	⬆️
t/10-tests_overview.t	100.00% <100.00%> (ø)
t/lib/OpenQA/Test/Utils.pm	78.83% <0.00%> (+0.27%)	⬆️

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