feat: limit job results on group overview and dashboard

[okurz]

Implement a limit on the number of jobs fetched for job group overview,
parent group overview, and the dashboard (consistent with the tests
overview page). This prevents performance issues and 502 errors when
accessing job groups with a huge number of jobs (e.g. >10k).

A warning message is displayed to the user when results are truncated.

I had started in

• perf: handle huge job groups gracefully #7026

until I realized that also the main index page aka "dashboard" of openQA
instances impacted. Also I found that we already have a limit for
/tests/overview that we can adapt here as well. And also regardless of
any optimization as done in #7026 we still benefit from a limit. I plan to
rebase #7026 on top and bump the default limit after optimization.

Related progress issue: https://progress.opensuse.org/issues/196913

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.87%. Comparing base (594c7e5) to head (96712f4).
⚠️ Report is 27 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #7058   +/-   ##
=======================================
  Coverage   99.87%   99.87%           
=======================================
  Files         418      418           
  Lines       44000    44075   +75     
=======================================
+ Hits        43945    44020   +75     
  Misses         55       55           

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[okurz]

Extended tests to cover the missing lines.

EDIT: … or so I thought

[d3flex]

Suggested change

	if (defined $max_jobs_limit && $total_jobs_seen >= $max_jobs_limit) {
	$limit_exceeded = $max_jobs_limit;
	last;
	}
	if (defined $max_jobs_limit && $total_jobs_seen >= $max_jobs_limit) {
	$limit_exceeded = $max_jobs_limit;
	last;
	}
	else {
	$remaining = $max_jobs_limit - $total_jobs_seen if defined $max_jobs_limit;
	}

increases the visibility/readability and decreases reduntant checks. it is cleaner

[okurz]

I don't understand. Removing the indendation will be invalid format. Maybe you just wanted to add the "else". But why does this additional "else" mixing pre-condition and post-condition increase visibility/readability?

[d3flex]

I need to say that many time I mark something as suggestion but it is not the exact code. it is more to show the intention. having said that, the purpose is to remove a second check as is in my $remaining = defined $max_jobs_limit ? $max_jobs_limit - $total_jobs_seen : undef; I think you can use only once the defined $max_jobs_limit and make it more easy to read and where the condition is involved.

[perlpunk]

I need to say that many time I mark something as suggestion but it is not the exact code.

It makes it harder for everyone else to understand, though.

You could have just indented it to make it understandable. If you click on the suggestion icon, the code is already indented, so it's not even a lot of work.

Regarding the suggestion:

If you have

if ($xy) {
    something;
    last;
}

then an else branch is useless.

having said that, the purpose is to remove a second check as is in my $remaining = defined $max_jobs_limit ? $max_jobs_limit - $total_jobs_seen : undef;

And it doesn't really reduce the number of times if defined $max_jobs_limit is called.

[d3flex]

you have a point (I think you are talking about semantics) but it doesnt address my initial review. the defined $max_jobs_limit appears twice. the question is whether can remove the second check (as Tina said even without else) and make it more clean/obvious/readable. it is small thing, which it will end up in the same functionality or leave it as is.

[okurz]

as perlpunk also explained there is no benefit to the suggestion so leaving this as is

[perlpunk]

@d3flex

but it doesnt address my initial review

I did.

the question is whether can remove the second check

Your suggestion does not remove a check.

Now this PR has been merged, so you can create another PR on top with your suggestion, then everyone can see what you mean.

[okurz]

rebased, fixed conflicts, ready for review