Consolidate error handling in HTTP

Method 1:
https://github.com/influxdata/influxdb/blob/feature/dbrp-api/kit/transport/http/api.go#L201

Method 2:
https://github.com/influxdata/influxdb/blob/feature/dbrp-api/kit/transport/http/error_handler.go#L18

We should really have one way to go.

Start by comparing the HTTP handling in kit/transport/http/api.go around line 201 with kit/transport/http/error_handler.go from the linked branch. Trace how each method reports errors and decide what a single handling path should cover. Done means the two approaches are consolidated into one consistent mechanism.

Written by the indexing model from the issue text.