Avoid checked PreImagesRepresentative calls

[fingolfin]

GAP 4.17 makes PreImagesRepresentative test membership in the image and adds an unchecked PreImagesRepresentativeNC. For maps into sphere groups with 6 generators the test runs a coset enumeration that overflows; for EpimorphismToOut it returns fail, since the randomised images of the generators need not span the range. SubFRMachine, marked sphere lifting, DistanceMarkedSpheres and
AutomorphismSphereMachine broke, and chapter-9-b.tst failed twice.

Call the NC variant at these sites. The elements are generators of the range of an isomorphism or epimorphism, except in SubFRMachine, which needs fail outside the image; the NC method returns fail there, as the unchecked method of GAP 4.16 did.

Assisted-by: Claude Code (Opus 5)

CC @ThomasBreuer @cdwensley

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 51.74%. Comparing base (f7eefd8) to head (b02016b).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
gap/machine.gi	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #38      +/-   ##
==========================================
+ Coverage   50.30%   51.74%   +1.43%     
==========================================
  Files          38       38              
  Lines        9317     9317              
  Branches      789      789              
==========================================
+ Hits         4687     4821     +134     
+ Misses       4595     4461     -134     
  Partials       35       35              

Files with missing lines	Coverage Δ
gap/markedsphere.gi	76.74% <100.00%> (ø)
gap/machine.gi	56.39% <80.00%> (+7.67%)	⬆️

... and 1 file with indirect coverage changes

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