Fix the server delete panic issue and enhance error logging

[Alva8756]

Replaced the boil.GetContextDB to sqlx.DB and tested in sandbox
Can create and delete servers successfully without panic
also checked into fleetdb pod log in the sandbox

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (5a0d102) 72.72% compared to head (f055e2e) 72.69%.

Files	Patch %	Lines
pkg/api/v1/router_server.go	40.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #16      +/-   ##
==========================================
- Coverage   72.72%   72.69%   -0.03%     
==========================================
  Files          38       38              
  Lines        3732     3736       +4     
==========================================
+ Hits         2714     2716       +2     
- Misses        760      762       +2     
  Partials      258      258              

Flag	Coverage Δ
unittests	72.69% <40.00%> (-0.03%)	⬇️

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