Use ES client for Connector API calls

[jedrazb]

Problem Description

We have a TemporaryConnectorAPIWrapper that calls the ES Connector API directly rather than using generated client methods.

With Connector API being part of ES client since 8.15 we should deprecate this code and use available client methods https://github.com/elastic/elasticsearch-specification/tree/main/specification/connector

E.g. see how we use connector.update_scheduling client method.

TODO

Swap direct Connector API calls with generated client methods. Remove TemporaryConnectorAPIWrapper class as is no longer needed.