Use longer exec probe timeouts for Head pods

[andrewsykim]

Why are these changes needed?

This is a follow-up to #2264 and #2265

For the Head pod, the exec probe timeout should be higher than 2 as exec probes run 2 "wget" commands:

wget -T 2 -q -O- http://localhost:52365/api/local_raylet_healthz | grep success
 && wget -T 2 -q -O- http://localhost:8265/api/gcs_healthz | grep success

This PR updates the probe timeout for Head pods to 5 seconds. See #2265 (comment) for more details.

Related issue number

#2264

Checks

• I've made sure the tests are passing.
• Testing Strategy
  • Unit tests
  • Manual tests
  • This PR is not tested :(

[andrewsykim]

I did more testing and I'm not sure that increasing the probe timeout is actually helping. Let's hold off on this PR for now, I will do more testing and report back

[andrewsykim]

I opened a separate PR to use HTTP probes which resolves some of the issues I'm encountering with exec probes: #2360

However, HTTP probes have a limitation of checking only a single endpoint