Fix clippy "unnecessary Ok" lints

zebra-consensus/src/checkpoint/list.rs

@@ -55,7 +55,7 @@ impl FromStr for CheckpointList {
             };
         }
 
-        Ok(CheckpointList::from_list(checkpoint_list)?)
+        CheckpointList::from_list(checkpoint_list)
     }
 }
 

zebrad/tests/acceptance.rs

@@ -783,7 +783,7 @@ fn sync_until(
         // This message is captured by the test runner, use
         // `cargo test -- --nocapture` to see it.
         eprintln!("Skipping network test because '$ZEBRA_SKIP_NETWORK_TESTS' is set.");
-        return Ok(testdir()?);
+        return testdir();
     }
 
     // Use a persistent state, so we can handle large syncs