Agent proxy passes escaped URL to scylla-server

[karol-kokoszka]

Root issue is here https://github.com/scylladb/scylla-enterprise/issues/4004

Alternator allows to use characters like ! in the column names.
Requests are sent to Scylla server with the escaped "!" already.
So, the url is /column_family/metrics/total_disk_space_used/alternator_geoip:geoip%21:networkHead-networkLastInt-index
.. instead of /column_family/metrics/total_disk_space_used/alternator_geoip:geoip!:networkHead-networkLastInt-index.

The character cannot be escaped before sending it to Scylla.

[karol-kokoszka]

Some more insides.
Escaping is done in the client generated from Scylla Manager to touch Scylla API.

The client is generated out of swagger files we keep here https://github.com/scylladb/scylla-manager/tree/master/swagger

We are still using Swagger 2.0.
I haven't find any option to change the easy way of instructing generator to not escape specified parameters.
This option is not available in Swagger 2.0, but it's available in OpenAPI 3.0.

https://swagger.io/docs/specification/serialization/
allowReserved in OpenAPI 3.0 serves the exact purpose that is needed here.

We must migrate from Swagger 2.0 to OpenAPI 3.0.

I'm removing milestone 3.2.7 - we need to plan this change.