[nfc][cxx-interop] Remove dead code in VisitClassTemplateDecl.

This is now handled in the namespace visitor. It will eventually be handled directly in the SILModulePrinter.

Refs swiftlang#38675.

Author: zoecarver

lib/ClangImporter/ImportDecl.cpp

@@ -4562,16 +4562,6 @@ namespace {
     }
 
     Decl *VisitClassTemplateDecl(const clang::ClassTemplateDecl *decl) {
-      // When loading a namespace's sub-decls, we won't add template
-      // specilizations, so make sure to do that here.
-      for (auto spec : decl->specializations()) {
-        if (auto importedSpec = Impl.importDecl(spec, getVersion())) {
-          if (auto namespaceDecl =
-                  dyn_cast<EnumDecl>(importedSpec->getDeclContext()))
-            namespaceDecl->addMember(importedSpec);
-        }
-      }
-
       ImportedName importedName;
       std::tie(importedName, std::ignore) = importFullName(decl);
       auto name = importedName.getDeclName().getBaseIdentifier();