[ANE-2237] make the preflight check filename unique

[spatten]

Overview

In ANE-2237, Lukas from SEW Eurodrive reported that the preflight check was failing around 10% of the time on their CI instance.

This was happening because they were running multiple runs of fossa in parallel, so the processes were sometimes deleting the preflight check file created by another instance of fossa, and it was raising an error when it tried to delete the nonexistent file.

Two obvious ways to fix this are to just not fail if you can't delete or to make the filename unique. I opted for the unique filename approach, but I have no strong opinion here.

Acceptance criteria

Testing plan

I was able to repro the initial problem by running this in one terminal:

while true; do rm -f $TMPDIR/preflight-check.txt; done

and then running fossa report a bunch of times in another:

repeat 20 { fossa report --format spdx-json --project zd-5344 --revision 2022-12-21T01:21:22Z attribution > /dev/null }

That's no longer going to reproduce the problem. So I just put in some logging and validated that the filename being returned by preflightCheckFilename was different between runs.

Risks

This is low risk

Metrics

References

ANE-2237

Checklist

• I added tests for this PR's change (or explained in the PR description why tests don't make sense).
• If this PR introduced a user-visible change, I added documentation into docs/.
• If this PR added docs, I added links as appropriate to the user manual's ToC in docs/README.ms and gave consideration to how discoverable or not my documentation is.
• If this change is externally visible, I updated Changelog.md. If this PR did not mark a release, I added my changes into an ## Unreleased section at the top.
• If I made changes to .fossa.yml or fossa-deps.{json.yml}, I updated docs/references/files/*.schema.json AND I have updated example files used by fossa init command. You may also need to update these if you have added/removed new dependency type (e.g. pip) or analysis target type (e.g. poetry).
• If I made changes to a subcommand's options, I updated docs/references/subcommands/<subcommand>.md.

[csasarak]

This is a nice find and fix!

[spatten]

This is a nice find and fix!

I can't really take credit for the find. Lukas from SEW Eurodrive was the one who pointed out that it was because they are running multiple scans on the same machine.

I'm just glad he did. This could have taken a while to figure out otherwise!

[lpanni]

I like the unique filename approach more than ignoring erorrs during deletion. Thanks for the quick fix!