[3.13] gh-109413: Enable mypy's `disallow_any_generics` setting when checking `libregrtest` (GH-127033) (#127034)

gh-109413: Enable mypy's `disallow_any_generics` setting when checking `libregrtest` (GH-127033)
(cherry picked from commit 824afbf548e7128ca57c6faf45cfd6b066a6ee45)

Co-authored-by: sobolevn <mail@sobolevn.me>