PBM. Add PBM CLI validation

[sandraromanchenko]

No description provided.

[Copilot]

Pull Request Overview

This PR adds comprehensive CLI validation tests for the PBM (Percona Backup for MongoDB) tool. The changes introduce a new test file that validates various PBM command-line interface commands and their error handling.

• Adds CLI validation tests for all major PBM commands (backup, restore, config, list, etc.)
• Implements Docker-based test environment setup with MongoDB replica set initialization
• Tests both valid and invalid parameter combinations with proper error message validation

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[Copilot]

The assertion message says the command 'should fail' but the assertion checks for success (rc == 0). This is contradictory and indicates either the assertion or the message is incorrect.

Suggested change

	assert result.rc == 0, "Delete-backup with --older-than should fail"
	assert result.rc != 0, "Delete-backup with --older-than should fail"

[Copilot]

This assertion checks for an exact error message string without using .lower() like other similar assertions in the file. For consistency and robustness, consider using .lower() to make the check case-insensitive.

Suggested change

	assert "specify a backup name, --time, or --external" in result.stderr
	assert "specify a backup name, --time, or --external" in result.stderr.lower()