Fix error when removing uploaded post breach file on config reset

[shreyamalviya]

Fixes:

os.remove(file_path) in monkey_island/cc/resources/pba_file_upload.py attempts to delete a directory which throws an error when the PBA_linux_filename/PBA_windows_filename field in the database is empty.

To reproduce:

1. Start Monkey Island.
2. Go to the configuration page.
3. Make sure that nothing is uploaded in the custom PBA file field.
4. Reset the config.

[codecov]

Codecov Report

Merging #1054 (1ad8249) into develop (753c058) will decrease coverage by 0.12%.
The diff coverage is 0.00%.

❗ Current head 1ad8249 differs from pull request most recent head 9b38303. Consider uploading reports for the commit 9b38303 to get more accurate results

@@             Coverage Diff             @@
##           develop    #1054      +/-   ##
===========================================
- Coverage    29.13%   29.01%   -0.13%     
===========================================
  Files          410      409       -1     
  Lines        12934    12912      -22     
===========================================
- Hits          3768     3746      -22     
  Misses        9166     9166              

Impacted Files	Coverage Δ
...nkey/monkey_island/cc/resources/pba_file_upload.py	0.00% <0.00%> (ø)
monkey/tests/conftest.py
monkey/tests/monkey_island/cc/conftest.py
...onkey/tests/infection_monkey/telemetry/conftest.py
monkey/monkey_island/cc/conftest.py	100.00% <0.00%> (ø)
...onkey/infection_monkey/telemetry/tests/conftest.py	100.00% <0.00%> (ø)
monkey/__init__.py	100.00% <0.00%> (+100.00%)	⬆️

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[mssalvatore]

It would be nice, but not mandatory, to add some tests for this function. I'm not sure if pytest plays nicely with the @jwt_required decorator.

[shreyamalviya]

@mssalvatore I'm not sure how much value we'll get out of adding tests for this.

[mssalvatore]

@mssalvatore I'm not sure how much value we'll get out of adding tests for this.

Had we had the tests in the first place, this bug might have been prevented. Where possible, we should try to first write a test that reproduces the issue, then fix it and see that the test passes. A set of tests for this function seems feasible. It's also a good opportunity to investigate the best way to test our API endpoints.

https://flask.palletsprojects.com/en/1.1.x/testing/

[mssalvatore]

I would recommend putting this method immediately after the one that calls it so as to follow the Stepdown rule

[mssalvatore]

Regarding the value of adding tests, does this function behave in a sane way if I pass an invalid value for file_type?