Remove redundant ignore-tidy-linelength annotations

This is step 2 towards fixing #77548.

In the codegen and codegen-units test suites, the `//` comment markers
were kept in order not to affect any source locations. This is because
these tests cannot be automatically `--bless`ed.

Author: sjakobi

src/test/codegen-units/item-collection/drop_in_place_intrinsic.rs

@@ -1,4 +1,4 @@
-// ignore-tidy-linelength
+//
 // compile-flags:-Zprint-mono-items=eager
 // compile-flags:-Zinline-in-all-cgus
 

src/test/codegen-units/item-collection/function-as-argument.rs

@@ -1,4 +1,4 @@
-// ignore-tidy-linelength
+//
 // compile-flags:-Zprint-mono-items=eager
 
 #![deny(dead_code)]