chore: restore initialize test for privateModule linter with correct wording

Author: thorimur

MathlibTest/PrivateModuleLinter/initialize.lean

@@ -2,11 +2,9 @@ module
 
 import Mathlib.Tactic.Linter.PrivateModule
 
-set_option linter.privateModule false -- Changed in nightly-testing, as this test no longer works.
-
 open Lean
 
--- Should not fire, since `initialize` creates a genuinely public declaration.
+-- Should not fire, since `initialize` has effects downstream despite creating a private decl here.
 initialize pure ()
 
 /- Check that we have indeed created a declaration, and aren't not linting just due to being an