refact pkg/database: clean up code and error messages

[mmetc]

No description provided.

[github-actions]

@mmetc: There are no area labels on this PR. You can add as many areas as you see fit.

• /area agent
• /area local-api
• /area cscli
• /area appsec
• /area security
• /area configuration

Details

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[codecov]

Codecov Report

Attention: Patch coverage is 82.35294% with 39 lines in your changes missing coverage. Please review.

Project coverage is 58.43%. Comparing base (c57dadc) to head (d0c7a33).

Files with missing lines	Patch %	Lines
pkg/database/alertfilter.go	86.53%	20 Missing and 8 partials ⚠️
pkg/database/alerts.go	0.00%	10 Missing ⚠️
pkg/types/ip.go	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3263      +/-   ##
==========================================
+ Coverage   58.41%   58.43%   +0.02%     
==========================================
  Files         351      352       +1     
  Lines       37748    37726      -22     
==========================================
- Hits        22050    22045       -5     
+ Misses      13802    13783      -19     
- Partials     1896     1898       +2     

Flag	Coverage Δ
bats	41.19% <71.49%> (-0.05%)	⬇️
unit-linux	34.41% <66.66%> (+<0.01%)	⬆️
unit-windows	29.67% <45.70%> (+0.01%)	⬆️

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