Add async/poll support for long-running pg_basebackup operations

[Copilot]

pg_basebackup for large databases can take hours, hitting Ansible's default 120s timeout during replica cloning.

Changes

• New configurable timeout: Added pg_basebackup_timeout (default: 14400s / 4 hours) in roles/postgres/replica/final/defaults/main.yml
• Async execution pattern: Modified pg_basebackup task to use async/poll: 0 with separate async_status wait loop
• Retry logic: Calculates retries as (timeout / 10) | int with minimum of 1, polls every 10 seconds
• Error handling: Preserves original rc != 0 or 'error' in stderr logic, adds safety checks for undefined variables

Usage

Override timeout in config.yml for very large databases:

cluster_vars:
  pg_basebackup_timeout: 28800  # 8 hours

Pattern follows existing roles/barman/first_backup/tasks/backup.yml implementation.

Original prompt

So, I want to add support for the tasks that could potentially take multiple hours to run on the remote nodes. For example, pg_basebackup of a large database when cloning to a standby. Tel

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