WIP: Isolate ARMBUILD-Ubuntu-24.04-arm CI for failure diagnosis

[hjmjohnson]

Summary

• Temporarily disable all CI pipelines except ARMBUILD-Ubuntu-24.04-arm to isolate and diagnose dashboard failures reported on ARM platforms
• GitHub Actions: Remove x86_64-rosetta and Python matrix entries from arm.yml; disable PR trigger in pixi.yml
• Azure Pipelines: Set pr: none for Linux, LinuxPython, MacOS, MacOSPython, Windows, WindowsPython

Context

CI logs show passing tests (0 failures) but CDash flags false-positive errors from test output containing error-like strings (e.g., "Test FAILED !" from itkConicShellInteriorExteriorSpatialFunctionTest, "ITK ERROR: Error" from itkMultiThreaderExceptionsTest, "FAILED: FIXME MetaImage library" from itkReadWriteImageWithDictionaryTest). This PR isolates the ARM Ubuntu build to diagnose these dashboard reporting issues.

This is a WIP commit — all CI changes will be reverted before merge.

Test plan

• Only ARMBUILD-Ubuntu-24.04-arm CI runs on this PR
• Verify dashboard error reporting against CI logs

🤖 Generated with Claude Code

[hjmjohnson]

@blowekamp

FYI: The following build warnings only show up under the linux arm builds:

└─[0] rg "warning: " 1_ARMBUILD-Ubuntu-24.04-arm.txt|fgrep -v libpng                             (isolate-arm-ci-failures|…1⚑9)
2026-03-13T23:54:34.6885757Z ../Modules/ThirdParty/Eigen3/src/itkeigen/Eigen/src/Core/products/SelfadjointMatrixVector.h:224:51: warning: 'result' may be used uninitialized [-Wmaybe-uninitialized]
2026-03-13T23:54:34.6934207Z ../Modules/ThirdParty/Eigen3/src/itkeigen/Eigen/src/Core/products/SelfadjointMatrixVector.h:224:51: warning: 'result' may be used uninitialized [-Wmaybe-uninitialized]
2026-03-13T23:54:34.6951147Z ../Modules/ThirdParty/Eigen3/src/itkeigen/Eigen/src/Core/products/SelfadjointMatrixVector.h:224:51: warning: 'result' may be used uninitialized [-Wmaybe-uninitialized]
2026-03-14T00:06:13.5784560Z ../Modules/ThirdParty/Eigen3/src/itkeigen/Eigen/src/Core/products/SelfadjointMatrixVector.h:224:51: warning: 'result' may be used uninitialized [-Wmaybe-uninitialized]
2026-03-14T00:06:56.2395410Z ../Modules/ThirdParty/Eigen3/src/itkeigen/Eigen/src/Core/products/SelfadjointMatrixVector.h:224:51: warning: 'result' may be used uninitialized [-Wmaybe-uninitialized]
2026-03-14T00:08:56.5683796Z ../Modules/ThirdParty/Eigen3/src/itkeigen/Eigen/src/Core/products/SelfadjointMatrixVector.h:224:51: warning: 'result' may be used uninitialized [-Wmaybe-uninitialized]
2026-03-14T00:24:19.7212980Z ../Modules/ThirdParty/Eigen3/src/itkeigen/Eigen/src/Core/products/SelfadjointMatrixVector.h:224:51: warning: 'result' may be used uninitialized [-Wmaybe-uninitialized]
2026-03-14T00:24:19.7420150Z ../Modules/ThirdParty/Eigen3/src/itkeigen/Eigen/src/Core/products/SelfadjointMatrixVector.h:224:51: warning: 'result' may be used uninitialized [-Wmaybe-uninitialized]

and there were some changes made to EIgen yesterday.

[hjmjohnson]

@blowekamp

A little AI evaluation of the differences for the passing and failing logs is narrowing down the issue with what look to be very plausible:

⏺ The ThirdParty patterns on lines 80-92 use a format like ".*[/\\][Mm]odules[/\\][Tt]hird[Pp]arty[/\\][Specific]..." but there's no Eigen3 entry. Lines 127 and 130 add GoogleTest and DoubleConversion entries. But the Eigen3 warnings have this path format:

../Modules/ThirdParty/Eigen3/src/itkeigen/Eigen/src/Core/...

Let me check if the existing ThirdParty warning exceptions match this. The patterns on lines 80-92 are for specific subdirectories (DICOMParser, Expat, JPEG, etc.) — there's no catch-all for all of ThirdParty.

The warning is: Eigen/src/Core/products/SelfadjointMatrixVector.h:224:51: warning: 'result' may be used uninitialized [-Wmaybe-uninitialized]

This only appears on GCC (Ubuntu ARM) and not on Clang (macOS Rosetta), which is typical for -Wmaybe-uninitialized — it's a GCC-only warning that Clang doesn't produce.

Root cause: The ARMBUILD-Ubuntu-24.04-arm CI fails because GCC on ARM produces 8 -Wmaybe-uninitialized warnings from Eigen3's SelfadjointMatrixVector.h, which are counted by ctest_build(NUMBER_WARNINGS build_warnings). The itk_common.cmake script (line 495-498) treats any
build_warnings > 0 as a CI failure. These Eigen3 warnings are not suppressed by CTEST_CUSTOM_WARNING_EXCEPTION because there's no pattern matching Eigen3 in the exception list — unlike other ThirdParty subdirectories (JPEG, TIFF, VNL, etc.) that each have their own exception
entry.

The Rosetta build passes because Clang doesn't emit -Wmaybe-uninitialized.

[hjmjohnson]

@blowekamp FYI:

⏺ Based on the analysis, the GCC -Wmaybe-uninitialized warnings from Eigen3's SelfadjointMatrixVector.h have been fixed upstream through a substantial rewrite of the algorithm. The warning-triggering code no longer exists in the upstream version.

[blowekamp]

@seanm ref#5876

There are more warnings suppression here for the third party than I realized:
https://github.com/InsightSoftwareConsortium/ITK/blob/main/CMake/CTestCustom.cmake.in#L80

Adding Eigen3 here seem reasonable if that is the convention. I am not sure how the changed yesterday caused this warning to be emitted, maybe it was already being suppressed somehow.