Fix assertion error in query planner with text search

[RobinTF]

This PR fixes #2483. Queries of the form

PREFIX textSearch: <https://qlever.cs.uni-freiburg.de/textSearch/>

SELECT ?p (count(distinct ?s) as ?cnt) WHERE {
    ?s ?p ?e
    SERVICE textSearch: {      
      ?t textSearch:contains [ textSearch:word "olympic" ] .
      ?t textSearch:contains [ textSearch:entity ?e ] .
	}
}  GROUP BY ?p

should work now. This also applies to other "magic service queries", but at least for spatial joins the pattern trick seems to mess with the query plan leading to different errors.

[RobinTF]

I'm not sure if we'd actually want this or if it would be better to always return false because the special service queries are special for a reason.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[sparql-conformance]

Overview

Number of Tests	Passed ✅	Failed ❌	Intended ⚠️	Not tested
525	439	19	67	0

Conformance check passed ✅

No test result changes.

Details: https://qlever.dev/sparql-conformance-ui?cur=25f27a44a25d22d3fe36b72c8072a2b754c7064b&prev=a8c9d865aac01c673ffa3b56758a12dbb94f7676

[codecov]

Codecov Report

❌ Patch coverage is 57.14286% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.11%. Comparing base (a8c9d86) to head (25f27a4).

Files with missing lines	Patch %	Lines
src/engine/CheckUsePatternTrick.cpp	57.14%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2488      +/-   ##
==========================================
+ Coverage   91.09%   91.11%   +0.01%     
==========================================
  Files         465      465              
  Lines       39690    39694       +4     
  Branches     5312     5313       +1     
==========================================
+ Hits        36155    36166      +11     
+ Misses       2020     2016       -4     
+ Partials     1515     1512       -3     

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