Remove accidental MB activation for RecentBlockhashes consistency fix (#11216)

(cherry picked from commit 7931579610)

Co-authored-by: Trent Nelson <trent@solana.com>

runtime/src/bank.rs

@@ -2832,8 +2832,8 @@ impl Bank {
     fn fix_recent_blockhashes_sysvar_delay(&self) -> bool {
         let activation_slot = match self.operating_mode() {
             OperatingMode::Development => 0,
-            OperatingMode::Stable => 26_444_256, // Epoch 74
             OperatingMode::Preview => Slot::MAX / 2,
+            OperatingMode::Stable => Slot::MAX / 2,
         };
 
         self.slot() >= activation_slot