fix(examples): Update examples for latest PETSc changes

[jrwrigh]

Purpose:

Update the examples to be compatible with the latest PETSc versions.

Note this will require updating the PETSc build on Noether.

LLM/GenAI Disclosure:

None

[jeremylt]

Working on the CI build update currently, will reply when ready

[jeremylt]

We also need to swap the test cases over to using ts_time_step instead of ts_dt

[jeremylt]

Huh, new issue: https://gitlab.com/libceed/libCEED/-/jobs/14025365570

[jrwrigh]

Looks like they're all CUDA backends. Did you revert the CUDA change in PETSc that we've been having to recycle?

commit 8176a7140471166274ad21eefd68452483cbaa22 (HEAD -> main)
Author: Jeremy <jeremy@jeremylt.org>
Date:   Mon Jun 16 17:14:11 2025 -0600

    Revert "CUVEC: fix copy from device to default to copy to device"

    This reverts commit 7ada2a5134eeb4113b6693316dd2660902f08a96.

We really should figure out what's going on there...

[jeremylt]

ah crap - I ran the rebuild script without reverting that one commit