COMP: Rename test names that collide with ITK core tests

[hjmjohnson]

Rename the two test names that collide with ITK core tests, which ITK's nightly dashboards report as AUTHOR_WARNINGs whenever this module is enabled.

Beyond the warning noise, duplicate test names share ITK's Cleanup_<name> fixture, so the colliding tests race under ctest -j.

The collision

itk_add_test keeps a global registry of test names (CMake/ITKModuleTest.cmake). Two names here are already registered by ITK core:

Test name	ITK core owner
itkGradientMagnitudeImageFilterTest1	Modules/Filtering/ImageGradient/test/CMakeLists.txt
itkCannyEdgeDetectionImageFilterTest2	Modules/Filtering/ImageFeature/test/CMakeLists.txt

ITK warns rather than fails for remote-module collisions, because they cannot be fixed in the ITK tree:

# Duplicate names share the Cleanup_<name> fixture and race under ctest -j.
# Remote modules live in separate repositories, so a collision they cause
# cannot be fixed in this tree; warn instead of failing the configure.

Observed on the ITK nightly Linux-Ubuntu-GCC-Doxygen (blaster.kitware), https://open.cdash.org/builds/11424939/configure — 2 warnings, both from this module. No other module in that build produces any.

The module's other ~48 test names are unique and unchanged.

Verification

Full ITK configure with -DModule_LesionSizingToolkit=ON, same source tree and build directory for both runs:

Configure	Duplicate test name warnings
ITK's currently pinned tag of this module	2 (reproduces the dashboard exactly)
Same tree with this change applied	0

Resulting ctest registrations — four distinct tests where there were two collisions:

#1792 itkCannyEdgeDetectionImageFilterTest2                        (ITK core)
#1933 itkGradientMagnitudeImageFilterTest1                         (ITK core)
#3722 LesionSizingToolkitGradientMagnitudeImageFilterTest1         (this module)
#3729 LesionSizingToolkitCannyEdgeDetectionImageFilterTest2        (this module)

Scope of the change: only the NAME argument of two itk_add_test calls. The executables, arguments, --compare baselines, and the .mha output filenames are untouched, and neither old name is referenced anywhere else in this repository.

Landing this does not by itself clear the dashboard warnings — ITK pins this module by commit in Modules/Remote/LesionSizingToolkit.remote.cmake (currently affbf7b0958205e2aab388bf0c3b7b1d5b0089de), so that pin needs bumping in a follow-up ITK change once this merges.

[hjmjohnson]

Just a test name change to remove conflicts with core ITK.