revert: fix: use zero gas price for empty blocks (#23094)

Reverts 2778a06

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: chee-chyuan

crates/rpc/rpc-eth-types/src/gas_oracle.rs

@@ -175,8 +175,7 @@ where
                 };
 
             if block_values.is_empty() {
-                // For empty blocks, use zero gas price to signal no demand
-                results.push(U256::ZERO);
+                results.push(U256::from(inner.last_price.price));
             } else {
                 results.extend(block_values);
                 populated_blocks += 1;