Remove legacy fields Protocol, Host, Path from Config struct in internal/pkg/remote/config.go

[pchila]

remote.Config struct contains fields Protocol, Host, Path that are initialized from the enroll command using the --url CLI option.
Fleet sends connection parameters in policy change action only using Hosts as a []string containing full URLs without splitting them into URL parts.

The goal of this issue is to refactor the enroll command to use the same field as we receive in the policy change action and remove the legacy fields to reduce the noise about fleet client configuration.

[elasticmachine]

Pinging @elastic/elastic-agent-control-plane (Team:Elastic-Agent-Control-Plane)

[elasticmachine]

Pinging @elastic/elastic-agent (Team:Elastic-Agent)