Remove clusterAgent.remoteDevelopmentAgentConfig field from GraphQL

MR: Pending

Description

• Remove clusterAgent.remoteDevelopmentAgentConfig from graphql.
• Also remove entire folder ee/spec/requests/api/graphql/remote_development/cluster_agent/remote_development_agent_config

Related: Remove deprecated API references to remote_deve... (#480769 - closed)

Acceptance Criteria

• Remove all references to field and related specs