chore: remove outdated allow-plugin directive

[lazysoundsystem]

Refs: OPS-9635

Composer sometimes prompts to allow or deny the preserve-paths plugin, even though it was removed some time ago. Not sure why it happens, but hoping it won't happen again.

[github-actions]

Coverage Report

Totals
Statements:	44.22% ( 1566 / 3541 )
Methods:	26.14% ( 23 / 88 )
Lines:	44.69% ( 1543 / 3453 )

[github-actions]

Build output

Composer Validate `success`

PHP Lint `success`

Docker Build `success`

Environment Setup `success`

Site Install `success`

PHP Code Sniffer `success`

Software Versions

```PHP 8.2.11 (cli) (built: Oct 6 2023 09:47:18) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.2.11, Copyright (c) Zend Technologies
with Zend OPcache v8.2.11, Copyright (c), by Zend Technologies
with Xdebug v3.2.1, Copyright (c) 2002-2023, by Derick Rethans
Composer version 2.6.5 2023-10-06 10:11:52
```

Pusher: @lazysoundsystem, Action: `pull_request`, Workflow: `Run tests``;