Enforce 5s timeout on all HTTP clients in kubelet-to-gcm

[courageJ]

PR Description: Enforce HTTP Client Timeouts in kubelet-to-gcm

Summary

Enforces a 5-second timeout on http.Client instances in kubelet-to-gcm to ensure requests finish within a predictable window and prevent potential goroutine build-up during slow backend responses.

Context

Currently, the http.Client defaults to an unbounded wait. This change adds a 5-second timeout to ensure that monitoring iterations remain isolated and do not accumulate if the Kubelet or GCE Metadata server is slow to respond.

Changes

• monitor/config/initialize.go: Added Timeout: 5 * time.Second to the http.Client used for GCE metadata retrieval.
• monitor/kubelet/source.go:
  • Added Timeout: 5 * time.Second to standard and secured Kubelet HTTP clients.
  • Added missing time package import.
• monitor/controller/source.go:
  • Added Timeout: 5 * time.Second to the Controller HTTP client.
  • Added missing time package import.

Verification

• Verified that all components compile successfully.
• Ran go test ./monitor/kubelet/... and confirmed that existing translation logic remains sound.
• All requests are now guaranteed to fail-fast within 5 seconds, which is safely below the 10-second polling interval.