cleanup CalcAccountsHashDataSource (#28882)

runtime/src/accounts_background_service.rs

@@ -297,7 +297,6 @@ impl SnapshotRequestHandler {
         let previous_hash = if test_hash_calculation {
             // We have to use the index version here.
             // We cannot calculate the non-index way because cache has not been flushed and stores don't match reality.
-            // This comment is out of date and can be re-evaluated.
             snapshot_root_bank.update_accounts_hash(
                 CalcAccountsHashDataSource::IndexForTests,
                 false,

runtime/src/accounts_db.rs

@@ -9587,8 +9587,8 @@ impl AccountsDb {
 
 /// Specify the source of the accounts data when calculating the accounts hash
 ///
-/// Using the Index is meant for tests and debugging; not intended during normal validator
-/// operation.
+/// Using the Index is meant for testing the hash calculation itself and debugging;
+/// not intended during normal validator operation.
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub enum CalcAccountsHashDataSource {
     IndexForTests,