Fix CLI race condition saving the config

[carmocca]

What does this PR do?

Fixes #11158

Test plan

No test as it's caused by a race condition. Testing it would require adding delays which are slow and flaky.

Does your PR introduce any breaking changes? If yes, please list them.

None

Before submitting

• Was this discussed/approved via a GitHub issue? (not for typos and docs)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure your PR does only one thing, instead of bundling different changes together?
• [n/a] Did you make sure to update the documentation with your changes? (if necessary)
• Did you write any new necessary tests? (not for typos and docs)
• Did you verify new and existing tests pass locally with your changes?
• Did you list all the breaking changes introduced by this pull request?
• Did you update the CHANGELOG? (not for typos, docs, test updates, or internal minor changes/refactorings)

PR review

• Is this pull request ready for review? (if not, please submit in draft mode)
• Check that all items from Before submitting are resolved
• Make sure the title is self-explanatory and the description concisely explains the PR
• Add labels and milestones (and optionally projects) to the PR so it can be classified

cc @Borda @carmocca @mauvilsa

[codecov]

Codecov Report

Merging #11199 (8799905) into master (235efb3) will decrease coverage by 0%.
The diff coverage is 100%.

❗ Current head 8799905 differs from pull request most recent head 015794b. Consider uploading reports for the commit 015794b to get more accurate results

@@           Coverage Diff            @@
##           master   #11199    +/-   ##
========================================
- Coverage      88%      88%    -0%     
========================================
  Files         177      177            
  Lines       16764    16557   -207     
========================================
- Hits        14782    14587   -195     
+ Misses       1982     1970    -12     

[awaelchli]

@carmocca in ModelCheckpoint we have the same code except that we use fs.exists. Should we make it consistent?

This special way of checking file existence with broadcast could even become a function, as we may reuse it in the future.

[carmocca]

Perhaps, but for a follow-up.

Do you think it should be part of checkpoint io?