feat(insights): Add fixed limits to concurrent report and source processing when uploading

[hk21702]

Add fixed limits to concurrent report and source processing when uploading.

Presently, the theoretical infinite number of goroutines can be spawned when the client is processing and uploading reports. Where r is the number of reports across all targeted sources and s is the number of targeted sources, there is a maximum limit of r+s goroutines that may be spawned, with r routines potentially attempting to send out HTTP requests.

There is a 150 report limit per source on how many reports are allowed to be on the disk. Typically, a collection call will remove old reports if there are too many already on the disk, limiting the impact of the go routine spawns. But it is possible for abuse to result in a considerable number of sources and reports that the uploader will treat as valid. Should the HTTP requests block or be stuck in retry loops, this can be problematic.

This PR also includes a test to ensure that the limits are being respected.

There is also a small fix to ensure that the root directory isn't being processed when traversing a directory to search for reports. This change doesn't cause any behavioral changes other than preventing a bit of unnecessary log spam.

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UDENG-7470

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.47%. Comparing base (04a7f87) to head (bc9d892).

Additional details and impacted files

@@                 Coverage Diff                 @@
##           buildtime-tests     #179      +/-   ##
===================================================
- Coverage            87.52%   87.47%   -0.05%     
===================================================
  Files                   50       50              
  Lines                 4311     4326      +15     
===================================================
+ Hits                  3773     3784      +11     
- Misses                 408      411       +3     
- Partials               130      131       +1     

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[CarlosNihelton]

I think we can improve resource consumption here.

[CarlosNihelton]

LGTM! Thanks for addressing yet this theoretical issue.