PHP 8.2: fixes for deprecated use of ${var} in strings

Summary:
Note that PHP 8.2 implemented this deprecation:

Using ${var} in strings is deprecated, use {$var} instead

This change fixes some known cases.

Ref T15196

Test Plan: - I checked with my big eyes that everything is as it should be

Reviewers: O1 Blessed Committers, avivey

Reviewed By: O1 Blessed Committers, avivey

Subscribers: avivey, speck, tobiaswiese, Matthew, Cigaryno

Maniphest Tasks: T15196

Differential Revision: https://we.phorge.it/D25098