[BE]: enable readability-delete-null-pointer clang-tidy check (#116107)

* Enables an additional clang-tidy check that remove unnecessary nullptr checks around delete statements.

Pull Request resolved: https://github.com/pytorch/pytorch/pull/116107
Approved by: https://github.com/albanD, https://github.com/malfet

.clang-tidy

@@ -52,6 +52,7 @@ modernize-*,
 -modernize-use-nodiscard,
 performance-*,
 readability-container-size-empty,
+readability-delete-null-pointer,
 readability-string-compare,
 '
 HeaderFilterRegex: '^(aten/|c10/|torch/).*$'