Update nsight_compute and nsight_systems building blocks with new default versions and distro support

[jilliebean]

Summary

• Bumps the default nsight_compute version from 2022.4.0 to 2026.2.1 and the default nsight_systems version from 2022.5.1 to 2026.4.1, matching the current releases available from NVIDIA's devtools package repository.
• Extends both building blocks' distro detection to cover Ubuntu 24.04, Ubuntu 26.04, RHEL 9, and RHEL 10 (and therefore Rocky Linux 9/10, which map to the RHEL branch), which previously topped out at Ubuntu 22.04 / RHEL 8.
• Updates docs/building_blocks.md to match the docstring changes.
• Verified against the live NVIDIA devtools repository (developer.download.nvidia.com/devtools/repos/) that the ubuntu2404, ubuntu2604, rhel9, and rhel10 paths exist and contain current nsight-compute/nsight-systems packages at the versions used here.

This addresses one of the outgoing maintainer's handoff TODOs to give the partially-maintained nsight_compute/nsight_systems building blocks an update pass.

Test plan

• ./runtests.sh --python3 — all 726 tests pass (718 baseline + 8 new distro test cases)
• Added new test cases for Ubuntu 24.04, Ubuntu 26.04, Rocky Linux 9, and Rocky Linux 10 for both building blocks
• Existing ppc64le-specific tests/branches left untouched (out of scope; already handled in the separate Power-removal PR)