SNOW-981533 Add 503 and contentType check for monitoring query response

[sfc-gh-dheyman]

Description

Please explain the changes you made here.

Checklist

• Code compiles correctly
• Run make fmt to fix inconsistent formats
• Run make lint to get lint errors and fix all of them
• Created tests which fail without the change (if possible)
• All tests passing
• Extended the README / documentation, if necessary

[codecov]

Codecov Report

Attention: 6 lines in your changes are missing coverage. Please review.

Comparison is base (15fac29) 82.48% compared to head (7b9044c) 82.74%.
Report is 1 commits behind head on master.

Files	Patch %	Lines
monitoring.go	53.84%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #981      +/-   ##
==========================================
+ Coverage   82.48%   82.74%   +0.26%     
==========================================
  Files          50       50              
  Lines        9643     9652       +9     
==========================================
+ Hits         7954     7987      +33     
+ Misses       1689     1665      -24     

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[sfc-gh-dheyman]

This solution won't fix the whole issue.