BUG: Many tests fail with 64-bit indices

[JDBetteridge]

Describe the bug
When Firedrake is build against a PETSc with 64-bit int indices a significant number of tests fail. Some are also crashing! See this CI run for reference:
https://github.com/firedrakeproject/firedrake/actions/runs/9905202548/job/27364244849?pr=3683

Steps to Reproduce
Steps to reproduce the behavior:

1. firedrake-install --petsc-int-type=int64
2. Run the Firedrake test suite pytest $VIRTUAL_ENV/src/firedrake/tests

Expected behavior
All tests should pass. Known int64 limitations should be marked and skipped, no tests should crash!

Error message
See this CI run
https://github.com/firedrakeproject/firedrake/actions/runs/9905202548/job/27364244849?pr=3683

Environment:

• CI

Additional Info
N/A