Auto merge of #14352 - Urgau:fix-cfgs-lint-name, r=weihanglo

Fix renamed disallowed cfg lint name

### What does this PR try to resolve?

In #14153 we allowed the to be merged rust-lang/rust#126158 lint. Since then an FCP was conducted and the lint was renamed to `explicit_builtin_cfgs_in_flags`. This PR renames the lint in the same test so that rust-lang/rust#126158 can be merged.

### Additional information

rust-lang/rust#126158 (comment) shows the failing test.

tests/testsuite/build.rs

@@ -6575,7 +6575,7 @@ fn user_specific_cfgs_are_filtered_out() {
         )
         .build();
 
-    p.cargo("rustc -- --cfg debug_assertions --cfg proc_macro -Aunknown_lints -Aunexpected_builtin_cfgs")
+    p.cargo("rustc -- --cfg debug_assertions --cfg proc_macro -Aunknown_lints -Aexplicit_builtin_cfgs_in_flags")
         .run();
     p.process(&p.bin("foo")).run();
 }