[awennersteen]

Note

This PR was prepared by Claude (an AI coding agent) at the request of @awennersteen. @awennersteen has not reviewed it yet and must review it before it is ready for anyone else.

Description of Change

• Remove _dump_environ(), which wrote every environment variable (including API keys) to the Slurm log at debug level.
• Log only the names of environment variables and --env: arguments; drop acquisition tokens from debug and error messages.
• Ignore {resource}_QRMI_JOB_ACQUISITION_TOKEN from the user job environment and export the freshly acquired token with OVERWRITE, so a job submitted from inside another QPU job cannot reuse (and later release) the parent session.
• README documents the above.

Supersedes #197 (whose branch now reverts #202 when compared with main). Part of #189.

Testing

• Builds with -Wall -Wextra against libslurm 23.11.
• Standalone harness for the --env: redaction and the token skip.
• Not run against a live Slurm cluster.

[awennersteen]

Need to look at this more closely. I did close #197 as being out of date. but I think that branch had better ideas. in particular the code needed to implement:

You can override QRMI logging independently of Slurm logging by setting
`RUST_LOG` in `plugstack.conf` with `--env:RUST_LOG=...`. The plugin applies
`--env:` arguments before QRMI is initialized, so the setting applies to both
daemon-side acquire/release calls and the job environment.

Examples:

```bash
# Slurm debug logs, but keep QRMI less verbose.
required /usr/lib64/slurm/spank_qrmi.so /etc/slurm/qrmi_config.json --env:RUST_LOG=warn

# QRMI debug logs without increasing Slurm's requested job verbosity.
required /usr/lib64/slurm/spank_qrmi.so /etc/slurm/qrmi_config.json --env:RUST_LOG=debug

# Target QRMI while keeping HTTP client logs quieter.
required /usr/lib64/slurm/spank_qrmi.so /etc/slurm/qrmi_config.json --env:RUST_LOG=qrmi=debug,reqwest=warn

QRMI records still pass through Slurm's logging APIs. QRMI debug records are
written with slurm_debug(), so Slurm's daemon log level must allow debug logs
for them to appear in slurmd.log. QRMI info, warn, and error records are
sent through Slurm info/error logging.

[awennersteen]

Rebased on main. The --env:RUST_LOG part from #197 is on main through #196: the README section with these examples is there, and --env: arguments are applied before _configure_qrmi_logging, so nothing from #197 needs to come into this PR. While rebasing I kept main's free() of the job acquisition token (#203 strdups it).