[coordinator] Make <500 endpoint errors as invalid params error

[Antanukas]

What this PR does / why we need it:

map <500 response codes to 400.

Special notes for your reviewer:

Makes sure 4xx errors are wrapped in InvalidParamsError that eventually gets mapped to 400 HTTP status code.
This is important because prometheus scraper retries 5xx errors. Before this change any errors returned from endpoint would have been mapped to 500.

Storage layer abstracts away HTTP so it's not possible to just respond with same status codes as in response from the endpoint. However it seems enough to map to 400 or 500 based on Prometheus scraper implementation.

Does this PR introduce a user-facing and/or backwards incompatible change?:

None

Does this PR require updating code package or user-facing documentation?:

None

[codecov]

Codecov Report

Merging #3783 (1583d16) into master (8028eef) will decrease coverage by 0.2%.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           master   #3783     +/-   ##
========================================
- Coverage    57.0%   56.8%   -0.3%     
========================================
  Files         552     552             
  Lines       63077   63077             
========================================
- Hits        35999   35867    -132     
- Misses      23892   24003    +111     
- Partials     3186    3207     +21     

Flag	Coverage Δ
aggregator	63.3% <ø> (-0.2%)	⬇️
cluster	∅ <ø> (∅)
collector	58.4% <ø> (ø)
dbnode	60.5% <ø> (-0.3%)	⬇️
m3em	46.4% <ø> (ø)
metrics	19.7% <ø> (ø)
msg	74.0% <ø> (-0.5%)	⬇️

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