[qa] Fix stale data bug in test_compactblocks_not_at_tip
[qa] Fix stale data bug in test_compactblocks_not_at_tip

Clear test_node.last_block before requesting blocks in the
compactblocks_not_at_tip test so comparisons won't fail if a blocks were received
before the test started.

The bug doesn't currently cause any problems due to the order tests run, but
this will change in the next commit.

Github-Pull: #9058
Rebased-From: 55bfddcabbf9e8a3743f77167ba4a43aaba9f948

okinc/bitcoin,bdelzell/creditcoin-org-creditcoin,oklink-dev/bitcoin,magacoin/magacoin,HashUnlimited/Einsteinium-Unlimited,jl2012/litecoin,bitcoinplusorg/xbcwalletsource,funkshelper/woodcore,litecoin-project/litecore-litecoin,Electronic-Gulden-Foundation/egulden,shaolinfry/litecoin,zetacoin/zetacoin,oklink-dev/bitcoin,itmanagerro/tresting,okinc/bitcoin,magacoin/magacoin,metacoin/florincoin,jl2012/litecoin,itmanagerro/tresting,shaolinfry/litecoin,emc2foundation/einsteinium,emc2foundation/einsteinium,zcoinofficial/zcoin,litecoin-project/litecore-litecoin,zetacoin/zetacoin,HashUnlimited/Einsteinium-Unlimited,funkshelper/woodcore,shaolinfry/litecoin,metacoin/florincoin,EntropyFactory/creativechain-core,ShadowMyst/creativechain-core,OmniLayer/omnicore,lbrtcoin/albertcoin,lbrtcoin/albertcoin,bdelzell/creditcoin-org-creditcoin,gravio-net/graviocoin,Electronic-Gulden-Foundation/egulden,okinc/bitcoin,litecoin-project/litecore-litecoin,lbrtcoin/albertcoin,funkshelper/woodcore,bitcoinplusorg/xbcwalletsource,ShadowMyst/creativechain-core,lbrtcoin/albertcoin,cannabiscoindev/cannabiscoin420,cannabiscoindev/cannabiscoin420,jl2012/litecoin,EntropyFactory/creativechain-core,bitcoinplusorg/xbcwalletsource,itmanagerro/tresting,bitcoinplusorg/xbcwalletsource,shaolinfry/litecoin,EntropyFactory/creativechain-core,cannabiscoindev/cannabiscoin420,magacoin/magacoin,HashUnlimited/Einsteinium-Unlimited,lbrtcoin/albertcoin,lbrtcoin/albertcoin,zetacoin/zetacoin,bdelzell/creditcoin-org-creditcoin,lbrtcoin/albertcoin,zcoinofficial/zcoin,Electronic-Gulden-Foundation/egulden,ShadowMyst/creativechain-core,emc2foundation/einsteinium,lbrtcoin/albertcoin,cannabiscoindev/cannabiscoin420,funkshelper/woodcore,gravio-net/graviocoin,bitcoinplusorg/xbcwalletsource,zcoinofficial/zcoin,zetacoin/zetacoin,zcoinofficial/zcoin,magacoin/magacoin,OmniLayer/omnicore,zcoinofficial/zcoin,metacoin/florincoin,oklink-dev/bitcoin,zcoinofficial/zcoin,okinc/bitcoin,ShadowMyst/creativechain-core,itmanagerro/tresting,bitcoinplusorg/xbcwalletsource,emc2foundation/einsteinium,metacoin/florincoin,jl2012/litecoin,oklink-dev/bitcoin,okinc/bitcoin,ShadowMyst/creativechain-core,lbrtcoin/albertcoin,emc2foundation/einsteinium,lbrtcoin/albertcoin,bdelzell/creditcoin-org-creditcoin,OmniLayer/omnicore,oklink-dev/bitcoin,metacoin/florincoin,Electronic-Gulden-Foundation/egulden,gravio-net/graviocoin,bdelzell/creditcoin-org-creditcoin,cannabiscoindev/cannabiscoin420,zetacoin/zetacoin,zcoinofficial/zcoin,lbrtcoin/albertcoin,magacoin/magacoin,jl2012/litecoin,okinc/bitcoin,EntropyFactory/creativechain-core,shaolinfry/litecoin,zcoinofficial/zcoin,litecoin-project/litecore-litecoin,OmniLayer/omnicore,emc2foundation/einsteinium,jl2012/litecoin,HashUnlimited/Einsteinium-Unlimited,shaolinfry/litecoin,ShadowMyst/creativechain-core,gravio-net/graviocoin,itmanagerro/tresting,cannabiscoindev/cannabiscoin420,gravio-net/graviocoin,OmniLayer/omnicore,Electronic-Gulden-Foundation/egulden,zcoinofficial/zcoin,lbrtcoin/albertcoin,bdelzell/creditcoin-org-creditcoin,EntropyFactory/creativechain-core,zcoinofficial/zcoin,gravio-net/graviocoin,metacoin/florincoin,OmniLayer/omnicore,HashUnlimited/Einsteinium-Unlimited,Electronic-Gulden-Foundation/egulden,HashUnlimited/Einsteinium-Unlimited,magacoin/magacoin,funkshelper/woodcore,zetacoin/zetacoin,litecoin-project/litecore-litecoin,itmanagerro/tresting,EntropyFactory/creativechain-core,litecoin-project/litecore-litecoin,oklink-dev/bitcoin