rpc: Remove deprecated migration code

Don't accept a second argument to `sendrawtransaction` and
`testmempoolaccept` of type `bool`. Actually even the code before this
change would not accept `bool`, but it would print a long explanatory
message when rejecting it: "Second argument must be numeric (maxfeerate)
and no longer supports a boolean. To allow a transaction with high fees,
set maxfeerate to 0."

This was scheduled for removal in 6c0a6f73e.

src/rpc/client.cpp

@@ -97,10 +97,8 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "signrawtransactionwithkey", 1, "privkeys" },
     { "signrawtransactionwithkey", 2, "prevtxs" },
     { "signrawtransactionwithwallet", 1, "prevtxs" },
-    { "sendrawtransaction", 1, "allowhighfees" },
     { "sendrawtransaction", 1, "maxfeerate" },
     { "testmempoolaccept", 0, "rawtxs" },
-    { "testmempoolaccept", 1, "allowhighfees" },
     { "testmempoolaccept", 1, "maxfeerate" },
     { "combinerawtransaction", 0, "txs" },
     { "fundrawtransaction", 1, "options" },