remove prev_rollup_block_hash from BaseBlock

proto/sequencerblockapis/astria/sequencerblock/v1alpha1/optimistic_block.proto

@@ -13,12 +13,10 @@ import "astria/primitive/v1/types.proto";
 message BaseBlock {
     // This is the block hash for the proposed block.
     bytes sequencer_block_hash = 1;
-    // The hash of previous rollup block, which new block will be created on top of.
-    bytes prev_rollup_block_hash = 3;
     // List of transactions to include in the new block.
-    repeated astria.sequencerblock.v1alpha1.RollupData transactions = 4;
+    repeated astria.sequencerblock.v1alpha1.RollupData transactions = 2;
     // Timestamp to be used for new block.
-    google.protobuf.Timestamp timestamp = 5;
+    google.protobuf.Timestamp timestamp = 3;
 }
 
 // Identifying metadata for blocks that have been successfully committed in the Sequencer.