development: webrequest: remove schema.
We agreed that logs generated by haproxykafka won't need to be compliant with Event Platform conventions.
We will treat the haproxykafka feed like we do for varnish, and will have ad hoc gobblin config to ingest the feed.
For this reason, a jsonschema in schema.wikimedia.org is not required.
cc / @aqu
Bug: T314956
Bug: T351117