plugin property "proxy_scheme" is unused

[Tieske]

The property is not used in the code since it is derived from the http request to make (always HTTPS in case of AWS Lambda). So the property should be removed from the schema.

This probably requires a migration.

[Tieske]

discussed with @bungle that removing fields do not need migrations, it's done automatically.

But it will break Konnect, since there is a mutually-required clause;

kong/kong/plugins/aws-lambda/schema.lua

Line 108 in 637456e

{ mutually_required = { "config.proxy_scheme", "config.proxy_url" } },

An option might be to first take out the mutually-required clause, and several versions later drop the field itself.

[gszr]

This was fixed by #8566.