Agent: Update protobuf definitions for agent configuration

MR - Update protobuf definitions for agent configura... (gitlab-org/cluster-integration/gitlab-agent!1581 - merged)

Description

Add default_max_hours_before_termination and max_hours_before_termination_limit to the agent's protobuf definition.

Implementation Details

in the agent repo, in file here, pkg/agentcfg/agentcfg.pb.go, and look at this RemoteDevelopmentCF struct.

After we finish the code update, we would need to run make regenerate-proto for generating language specific code, and commit together

Acceptance Criteria

• default_max_hours_before_termination and max_hours_before_termination_limit are added to the agent probotbuf definition.
• Both fields are integers.
• No other validations are required on the agent.