Harden Android NDK setup against apt mirror outages

[Copilot]

Description

Android CI Pipeline failed in Setup Android NDK before build/test due to transient apt connectivity to azure.archive.ubuntu.com.
This change makes the package bootstrap resilient so Android jobs proceed when the primary Ubuntu mirror is flaky.

• NDK setup bootstrap hardening

  • Short-circuit install when ninja and realpath are already present.
  • Replace one-shot apt install with bounded retries.
  • On repeated failure, rewrite Ubuntu mirror from Azure mirror to archive.ubuntu.com and retry.

• Mirror fallback correctness

  • Use a URL pattern that matches both http and https Azure mirror entries.

if ! retry_apt_install; then
  sudo sed -i 's|https\?://azure.archive.ubuntu.com/ubuntu|http://archive.ubuntu.com/ubuntu|g' /etc/apt/sources.list
  retry_apt_install
fi

Motivation and Context

Android CI Pipeline (job 82229165144) failed because apt could not fetch ninja-build from azure.archive.ubuntu.com (timeout), causing early exit in the shared Android NDK setup action.
The workflow now tolerates transient mirror/network failures without changing downstream build logic.