init: replace Result<> with expected<>

Android-base has an implementation of the future std::expected<>.
This provides the same baseline functionality as Result<>, so use it
instead of our own version.

Bug: 132145659
Test: boot, init unit tests
Change-Id: I11e61bcb5719b262a6420483ed51a762826a9e23
diff --git a/init/rlimit_parser.cpp b/init/rlimit_parser.cpp
index 1e0754a..476a46a 100644
--- a/init/rlimit_parser.cpp
+++ b/init/rlimit_parser.cpp
@@ -77,7 +77,7 @@
         return Error() << "Could not parse hard limit '" << args[3] << "'";
     }
 
-    return {resource, limit};
+    return std::pair{resource, limit};
 }
 
 }  // namespace init