chore: Always use request metadata in backward compatibility test (#2690)

This is a preparation step for [making request metadata
non-optional](#2622). This will ensure
further changes to the hashes affected by this change are due to
something else (in a followup).

Author: stiegerc

rs/state_manager/src/tree_hash.rs

@@ -219,7 +219,7 @@ mod tests {
             for i in 1..6 {
                 stream.push(
                     RequestBuilder::new()
-                        .metadata((i % 5 != 0).then_some(RequestMetadata::new(
+                        .metadata(Some(RequestMetadata::new(
                             i % 3,
                             Time::from_nanos_since_unix_epoch(i % 2),
                         )))
@@ -358,9 +358,9 @@ mod tests {
         // BACKWARD COMPATIBILITY CODE FOR OLD CERTIFICATION VERSIONS THAT
         // NEED TO BE SUPPORTED.
         let expected_hashes: [&str; 3] = [
-            "D13F75C42D3E2BDA2F742510029088A9ADB119E30241AC969DE24936489168B5",
-            "E739B8EA1585E9BB97988C80ED0C0CDFDF064D4BC5A2B6B06EB414BFF6139CCE",
-            "31F4593CC82CDB0B858F190E00112AF4599B5333F7AED9403EEAE88B656738D5",
+            "0BD567305B9828C7BDE2A03E25871C382742A2598308761A47745BAA9E3495FF",
+            "28BCC63FA7C215C8308EE8201CDEBDC06B62AFB2E9F4C2AB31452A4DBBD73B90",
+            "4677DFA14CC8B349B1F0D88651CD961FE8DF2E905C3C886B9116972D798B1C1E",
         ];
         assert_eq!(expected_hashes.len(), all_supported_versions().count());