docs: remove stale NCO Google Calendar TEMPLATE links

[TineoC]

Summary

• Remove Sep 2024 Google Calendar TEMPLATE links from the New Contributor Orientation README.
• Keep typical EMEA/AMER timing text and point people at the live community calendar (k8s.dev/calendar / kubernetes.dev calendar) for confirmed sessions.

Companion to kubernetes/contributor-site#782 — orientation _index.md on the contributor site is synced from this file via gen-content.

Test plan

• Confirm Meetings section no longer links to calendar.google.com/...TEMPLATE...20240917
• Confirm typical session times and calendar/mailing-list guidance remain readable
• After merge + contributor-site content sync, orientation page no longer shows stale TEMPLATE hrefs below the live NCO card

[kubernetes-prow]

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