feat(ansible): add pgBackRest tasks and configurations

[jchancojr]

What kind of change does this PR introduce?

Feature- pgBackRest backup solution

What is the current behavior?

pgBackRest tasks and configs are absent

What is the new behavior?

pgBackRest tasks and configs are missing are present

Additional context

NA

Summary by CodeRabbit

• New Features

  • Adds pgBackRest support with configurable global and repository settings (S3 storage, retention, encryption, compression, performance and logging). Some async/archive options remain as commented placeholders.

• Chores / Install

  • Adds automated install and setup: package install, user/group and sudoers provisioning, directory creation, config placement and a safe wrapper for invoking pgBackRest.
  • Updates packaged PostgreSQL release references.

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[jchancojr]

test-postgres-engines-with-smoke.sh

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Test Summary
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ENGINE          RESULT
------          ------
15              PASSED (375s)
17              PASSED (352s)
17-oriole       PASSED (367s)

============================================================
Total: 3 | Passed: 3 | Failed: 0
============================================================

[INFO] Postgres commit: add0a0f372300387e01d5652e45d077143861a83