chore: use the new reloadable config api in reporting

[atzoum]

Description

Only Event schemas v1 is now left using the old config api, which shall be removed altogether in the next release

Security

• The code changed/added as part of this pull request won't create any security issues with how the software is being used.

[codecov]

Codecov Report

Patch coverage: 45.16% and project coverage change: +0.15% 🎉

Comparison is base (01a0737) 69.16% compared to head (fe3c70b) 69.31%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3909      +/-   ##
==========================================
+ Coverage   69.16%   69.31%   +0.15%     
==========================================
  Files         353      353              
  Lines       52905    52900       -5     
==========================================
+ Hits        36592    36668      +76     
+ Misses      13996    13926      -70     
+ Partials     2317     2306      -11     

Files Changed	Coverage Δ
enterprise/reporting/reporting.go	29.91% <41.66%> (-0.09%)	⬇️
enterprise/reporting/error_reporting.go	21.51% <57.14%> (-0.48%)	⬇️

... and 13 files with indirect coverage changes

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