test: remove unecessary `decoderawtransaction` calls

In `wallet_fundrawtransaction`, there are some unecessary
variables/calls to `decoderawtransaction`. They have not
been used.

test/functional/wallet_fundrawtransaction.py

@@ -183,7 +183,6 @@ class RawTransactionsTest(BitcoinTestFramework):
         inputs  = [ ]
         outputs = { self.nodes[0].getnewaddress() : 1.0 }
         rawtx   = self.nodes[2].createrawtransaction(inputs, outputs)
-        dec_tx  = self.nodes[2].decoderawtransaction(rawtx)
         rawtxfund = self.nodes[2].fundrawtransaction(rawtx)
         dec_tx  = self.nodes[2].decoderawtransaction(rawtxfund['hex'])
         assert len(dec_tx['vin']) > 0  #test that we have enough inputs
@@ -193,8 +192,6 @@ class RawTransactionsTest(BitcoinTestFramework):
         inputs  = [ ]
         outputs = { self.nodes[0].getnewaddress() : 2.2 }
         rawtx   = self.nodes[2].createrawtransaction(inputs, outputs)
-        dec_tx  = self.nodes[2].decoderawtransaction(rawtx)
-
         rawtxfund = self.nodes[2].fundrawtransaction(rawtx)
         dec_tx  = self.nodes[2].decoderawtransaction(rawtxfund['hex'])
         assert len(dec_tx['vin']) > 0  #test if we have enough inputs
@@ -206,7 +203,6 @@ class RawTransactionsTest(BitcoinTestFramework):
         inputs  = [ ]
         outputs = { self.nodes[0].getnewaddress() : 2.6, self.nodes[1].getnewaddress() : 2.5 }
         rawtx   = self.nodes[2].createrawtransaction(inputs, outputs)
-        dec_tx  = self.nodes[2].decoderawtransaction(rawtx)
 
         rawtxfund = self.nodes[2].fundrawtransaction(rawtx)
         dec_tx  = self.nodes[2].decoderawtransaction(rawtxfund['hex'])
@@ -364,7 +360,6 @@ class RawTransactionsTest(BitcoinTestFramework):
         # Should fail without add_inputs:
         assert_raises_rpc_error(-4, ERR_NOT_ENOUGH_PRESET_INPUTS, self.nodes[2].fundrawtransaction, rawtx, add_inputs=False)
         rawtxfund = self.nodes[2].fundrawtransaction(rawtx, add_inputs=True)
-
         dec_tx  = self.nodes[2].decoderawtransaction(rawtxfund['hex'])
         totalOut = 0
         matchingOuts = 0