Add test for multiple patch delete in strategic merge patches

[cappyzawa]

This test verifies that multiple $patch: delete directives in a single strategic merge patch work correctly. The test currently fails due to a panic in kustomize (upstream issue kubernetes-sigs/kustomize#5552), but will pass once the fix is included in a future kustomize release.

Ref: https://github.com/fluxcd/kustomize-controller/issues/1306