refactor: remove min-buy-in param (#135)

Co-authored-by: David Terpay <35130517+davidterpay@users.noreply.github.com>

proto/pob/builder/v1/genesis.proto

@@ -8,7 +8,9 @@ import "amino/amino.proto";
 option go_package = "github.com/skip-mev/pob/x/builder/types";
 
 // GenesisState defines the genesis state of the x/builder module.
-message GenesisState { Params params = 1 [ (gogoproto.nullable) = false ]; }
+message GenesisState {
+  Params params = 1 [(gogoproto.nullable) = false];
+}
 
 // Params defines the parameters of the x/builder module.
 message Params {
@@ -24,26 +26,21 @@ message Params {
 
   // reserve_fee specifies the bid floor for the auction.
   cosmos.base.v1beta1.Coin reserve_fee = 3
-      [ (gogoproto.nullable) = false, (amino.dont_omitempty) = true ];
-
-  // min_buy_in_fee specifies the fee that the bidder must pay to enter the
-  // auction.
-  cosmos.base.v1beta1.Coin min_buy_in_fee = 4
-      [ (gogoproto.nullable) = false, (amino.dont_omitempty) = true ];
+      [(gogoproto.nullable) = false, (amino.dont_omitempty) = true];
 
   // min_bid_increment specifies the minimum amount that the next bid must be
   // greater than the previous bid.
-  cosmos.base.v1beta1.Coin min_bid_increment = 5
-      [ (gogoproto.nullable) = false, (amino.dont_omitempty) = true ];
+  cosmos.base.v1beta1.Coin min_bid_increment = 4
+      [(gogoproto.nullable) = false, (amino.dont_omitempty) = true];
 
   // front_running_protection specifies whether front running and sandwich
   // attack protection is enabled.
-  bool front_running_protection = 6;
+  bool front_running_protection = 5;
 
   // proposer_fee defines the portion of the winning bid that goes to the block
   // proposer that proposed the block.
-  string proposer_fee = 7 [
-    (gogoproto.nullable) = false,
+  string proposer_fee = 6 [
+    (gogoproto.nullable)   = false,
     (gogoproto.customtype) = "github.com/cosmos/cosmos-sdk/types.Dec"
   ];
-}
+}