Remove dcrd RPC MixPairRequests.

The MixPairRequests RPC is longer used in this repo and in dcrd it is marked as "WARNING: This is experimental and will very likely be removed in the next version.  Do not use!"

Author: jholdstock

rpc/client/dcrd/calls.go

@@ -1,4 +1,4 @@
-// Copyright (c) 2019 The Decred developers
+// Copyright (c) 2019-2026 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -304,19 +304,6 @@ func (r *RPC) MixMessage(ctx context.Context, hash *chainhash.Hash) (mixing.Mess
 	return msg, err
 }
 
-// MixPairRequests returns all mixing pair request messages currently held by
-// the dcrd mixpool.
-func (r *RPC) MixPairRequests(ctx context.Context) ([]*wire.MsgMixPairReq, error) {
-	const op errors.Op = "dcrd.MixPairRequests"
-
-	mixPRs := makeMessageArray[wire.MsgMixPairReq](wire.MixVersion)
-	err := r.Call(ctx, "getmixpairrequests", &mixPRs)
-	if err != nil {
-		return nil, errors.E(op, err)
-	}
-	return mixPRs.Messages, nil
-}
-
 // Blocks returns the blocks for each block hash.
 func (r *RPC) Blocks(ctx context.Context, blockHashes []*chainhash.Hash) ([]*wire.MsgBlock, error) {
 	const op errors.Op = "dcrd.Blocks"