Jenkins srun updates

[lsawade]

Description

Updates

• gcc job to run with fewer cores and less time (combination should hold)
• intel job to run with fewer cores and less time (combination should hold)
• nvidia job unchanged
• mpi job, at least 2 nodes max 8 with ntasks total

Issue Number

-/-

Checklist

Please make sure to check developer documentation on specfem docs.

• I ran the code through pre-commit to check style
• THE DOCUMENTATION BUILDS WITHOUT WARNINGS/ERRORS
• I have added labels to the PR (see right hand side of the PR page)
• My code passes all the integration tests
• I have added sufficient unittests to test my changes
• I have added/updated documentation for the changes I am proposing
• I have updated CMakeLists to ensure my code builds
• My code builds across all platforms