Clean up feature preventing new rent-paying accounts (solana-labs#26000)

* Clean up require_rent_exempt_accounts feature

* Fix tests in bank_client, system_instruction_processor

* Fix tests in snapshot_utils

* Fix bank tests

* Ignore rent tests

* Fix stake-accounts tests

runtime/src/accounts.rs

@@ -427,22 +427,15 @@ impl Accounts {
             .map_err(|_| TransactionError::InsufficientFundsForFee)?;
 
         let payer_post_rent_state = RentState::from_account(payer_account, &rent_collector.rent);
-        let rent_state_result = check_rent_state_with_account(
+        check_rent_state_with_account(
             &payer_pre_rent_state,
             &payer_post_rent_state,
             payer_address,
             payer_account,
             feature_set
                 .is_active(&feature_set::include_account_index_in_rent_error::ID)
                 .then(|| payer_index),
-        );
-        // Feature gate only wraps the actual error return so that the metrics and debug
-        // logging generated by `check_rent_state_with_account()` can be examined before
-        // feature activation
-        if feature_set.is_active(&feature_set::require_rent_exempt_accounts::id()) {
-            rent_state_result?;
-        }
-        Ok(())
+        )
     }
 
     fn load_executable_accounts(