test(samples): add liveness/readiness probes to sample apps

[andrewazores]

Welcome to Cryostat! 👋

Before contributing, make sure you have:

• Read the contributing guidelines
• Linked a relevant issue which this PR resolves
• Linked any other relevant issues, PR's, or documentation, if any
• Resolved all conflicts, if any
• Rebased your branch PR on top of the latest upstream main branch
• Attached at least one of the following labels to the PR: [chore, ci, docs, feat, fix, test]
• Signed all commits: git commit -S -m "YOUR_COMMIT_MESSAGE"

---

Related to cryostatio/cryostat-agent#634

Description of the change:

Adds liveness and readiness probes to two of the sample app definitions. These are the two that represent the common cases - an Agent-less application that is discovered by Endpoints (EndpointSlice) and uses JMX, and an autoconfig-injected Agent.

Motivation for the change:

Make these two sample app cases more representative of real production workloads which should be expected to use liveness and readiness probes.

How to manually test:

1. Deploy Operator, create CR, etc. as usual
2. make sample_app and make sample_app_agent_injected as usual, ensuring that discovery for both works as usual and that Kubernetes reports both as alive and ready to accept traffic. Check the injected Agent's logs in the application Pod and observe that initially, the Agent fails to resolve its own callback URL (hostname), but once the pod probes succeed then the Agent becomes able to resolve itself and proceeds with Cryostat registration.