ci: fix CODEOWNERS for ngcc (angular#29660)

With a770aa2, ngcc was moved to a different directory
(`compiler/src/ngcc/` --> `compiler/ngcc/`), but the `CODEOWNERS` file
was not updated to reflect that.
PR Close angular#29660

Author: gkalpak

.github/CODEOWNERS

@@ -399,10 +399,10 @@
 
 
 # ================================================
-#  packages/compiler-cli/src/ngcc/
+#  packages/compiler-cli/ngcc/
 # ================================================
 
-/packages/compiler-cli/src/ngcc/**                              @angular/fw-ngcc @angular/framework-global-approvers
+/packages/compiler-cli/ngcc/**                                  @angular/fw-ngcc @angular/framework-global-approvers