Fix RPC/pruneblockchain returned prune height
Fix RPC/pruneblockchain returned prune height

Github-Pull: #15991
Rebased-From: 97f517dd851450b1ede1eb6b20f77691883a7737

vertcoin/vertcoin,qtumproject/qtum,untrustbank/litecoin,qtumproject/qtum,untrustbank/litecoin,qtumproject/qtum,myriadcoin/myriadcoin,ahmedbodi/vertcoin,GroestlCoin/GroestlCoin,untrustbank/litecoin,ahmedbodi/vertcoin,bespike/litecoin,untrustbank/litecoin,GroestlCoin/GroestlCoin,GroestlCoin/bitcoin,GroestlCoin/bitcoin,bespike/litecoin,ahmedbodi/vertcoin,vertcoin/vertcoin,ahmedbodi/vertcoin,untrustbank/litecoin,myriadteam/myriadcoin,GroestlCoin/GroestlCoin,GroestlCoin/bitcoin,GroestlCoin/GroestlCoin,vertcoin/vertcoin,bespike/litecoin,qtumproject/qtum,GroestlCoin/bitcoin,vertcoin/vertcoin,myriadteam/myriadcoin,vertcoin/vertcoin,myriadcoin/myriadcoin,qtumproject/qtum,myriadteam/myriadcoin,vertcoin/vertcoin,qtumproject/qtum,bespike/litecoin,GroestlCoin/bitcoin,untrustbank/litecoin,GroestlCoin/GroestlCoin,myriadteam/myriadcoin,myriadcoin/myriadcoin,myriadcoin/myriadcoin,myriadcoin/myriadcoin,qtumproject/qtum,GroestlCoin/GroestlCoin,GroestlCoin/bitcoin,bespike/litecoin,bespike/litecoin,ahmedbodi/vertcoin,ahmedbodi/vertcoin,myriadcoin/myriadcoin,myriadteam/myriadcoin,myriadteam/myriadcoin