nix3-profile: remove check "name" attr in manifests

It doesn't seem to have ever been used.

Based off of commit a748e88bf4cca0fdc6ce75188e88017a7899d16b

Upstream-PR: https://github.com/NixOS/nix/pull/9656
Change-Id: Idcf250a645fa43f2ef11fb15b503b070a62a917e

src/libcmd/cmd-profiles.cc

@@ -153,8 +153,6 @@ ProfileManifest::ProfileManifest(EvalState & state, const Path & profile)
             std::string name =
                 elems.is_object()
                 ? elem.key()
-                : e.contains("name")
-                ? static_cast<std::string>(e["name"])
                 : element.source
                 ? getNameFromURL(parseURL(element.source->to_string())).value_or(element.identifier())
                 : element.identifier();