enhance custom easyblock for SuperLU to allow oversubscription when running tests

[casparvl]

Essentially does the same as #3884 does, but for SuperLU_DIST

[casparvl]

Test report by @casparvl

Overview of tested easyconfigs (in order)

• SUCCESS SuperLU_DIST-9.1.0-foss-2025a.eb
• SUCCESS SuperLU_DIST-8.2.1-foss-2023b.eb

Build succeeded for 2 out of 2 (2 easyconfigs in total)
tcn387.local.snellius.surf.nl - Linux RHEL 9.4, x86_64, AMD EPYC 7H12 64-Core Processor, Python 3.9.18
See https://gist.github.com/casparvl/708f99ef1a73aad0bab7d88c6c7077da for a full test report.

[branfosj]

Test report by @branfosj

Overview of tested easyconfigs (in order)

• SUCCESS ParMETIS-4.0.3-gompi-2024a.eb
• SUCCESS ParMETIS-4.0.3-gompi-2025a.eb
• SUCCESS SuperLU_DIST-9.1.0-foss-2024a.eb
• SUCCESS SuperLU_DIST-9.1.0-foss-2025a.eb
• SUCCESS OpenMPI-4.1.6-GCC-13.2.0.eb
• SUCCESS gompi-2023b.eb
• SUCCESS FFTW.MPI-3.3.10-gompi-2023b.eb
• SUCCESS ScaLAPACK-2.2.0-gompi-2023b-fb.eb
• SUCCESS foss-2023b.eb
• SUCCESS SuperLU-6.0.1-foss-2023b.eb

Build succeeded for 10 out of 10 (3 easyconfigs in total)
bear-pg0210u03a - Linux RHEL 8.10, x86_64, Intel(R) Xeon(R) Platinum 8480CL (sapphirerapids), Python 3.6.8
See https://gist.github.com/branfosj/c5ca0493d90b54ed6fb3982ecf9ea54a for a full test report.

[branfosj]

Going in, thanks @casparvl!