ci: Add explanation in forbidigo (#12140)

.golangci.yml

@@ -61,8 +61,8 @@ linters-settings:
   forbidigo:
     # Forbid the following identifiers (list of regexp).
     forbid:
-      - '\brequire\.New\b'
+      - '\brequire\.New\b(# Use package-level functions with explicit TestingT)?'
-      - '\bassert\.New\b'
+      - '\bassert\.New\b(# Use package-level functions with explicit TestingT)?'
     # Exclude godoc examples from forbidigo checks.
     # Default: true
     exclude_godoc_examples: false