docs(user-manuals): update deprecated v1beta2 scheduler API to v1

[mdryaaan]

Summary

• Replace kubescheduler.config.k8s.io/v1beta2 with kubescheduler.config.k8s.io/v1 in all KubeSchedulerConfiguration examples — v1beta2 was removed in
  Kubernetes 1.26 and will error on any cluster running >= 1.26

Files Changed

• docs/user-manuals/capacity-scheduling.md — 2 occurrences updated (KubeSchedulerConfiguration and ElasticQuotaArgs apiVersion)
• docs/user-manuals/gang-scheduling.md — 2 occurrences updated (KubeSchedulerConfiguration and CoschedulingArgs apiVersion)
• versioned_docs/version-v1.8/user-manuals/capacity-scheduling.md — same 2 occurrences
• versioned_docs/version-v1.8/user-manuals/gang-scheduling.md — same 2 occurrences

Fixes #332

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