chore(eap-noob): use slices.Contains instead of a hand-rolled helper

[woodsonl]

Description

Drops the hand-rolled containsInt helper in eap-noob and uses
slices.Contains from the standard library at its three call sites. No
behavior change.

Release intent

Changelog title

n/a

Changelog body

n/a

Bumps

• services: none
• nvpair-cluster-manager: none
• nvpair-engine-manager: none
• nvpair-errors: none
• nvpair-job-scheduler: none
• nvpair-manual-nodes: none
• nvpair-node-info: none
• nvpair-node-scanner: none
• nvpair-node-settings: none
• nvpair-proxy: none
• nvpair-tui: none
• nvpair-ui-broker: none
• nvpair-workload-manager: none

Scope

Included: the helper removal and the three call-site changes.
eap-noob is an internal library, so no service binary's behavior changes.

Excluded: nothing else.

Validation

• go build ./... and go test ./... in services/eap-noob

Risk

None. Pure standard-library substitution.

Checklist

• I have read the Contributing Guidelines.
• Every commit is signed off (git commit -s), certifying the Developer Certificate of Origin.
• New or existing tests cover the change.
• Relevant documentation is updated.
• I checked the diff, changed filenames, and commit messages for credentials, private data, internal URLs, internal issue identifiers, and generated artifacts.
• I recorded the validation commands and results above.
• I declared version bumps in the release-intent block above. services/versions.json is written by automation — do not edit it by hand.