wallet: Change log interval to use `steady_clock`
wallet: Change log interval to use `steady_clock`

This refactors the log interval variables to use `steady_clock`
as it is best suitable for measuring intervals.

particl/particl-core,kallewoof/bitcoin,GroestlCoin/GroestlCoin,andreaskern/bitcoin,jamesob/bitcoin,mruddy/bitcoin,AkioNak/bitcoin,AkioNak/bitcoin,jamesob/bitcoin,fanquake/bitcoin,namecoin/namecoin-core,domob1812/bitcoin,ajtowns/bitcoin,Xekyo/bitcoin,fanquake/bitcoin,fanquake/bitcoin,jambolo/bitcoin,kallewoof/bitcoin,sstone/bitcoin,domob1812/bitcoin,anditto/bitcoin,mruddy/bitcoin,anditto/bitcoin,fujicoin/fujicoin,fujicoin/fujicoin,GroestlCoin/bitcoin,domob1812/bitcoin,instagibbs/bitcoin,fanquake/bitcoin,domob1812/bitcoin,lateminer/bitcoin,tecnovert/particl-core,Xekyo/bitcoin,namecoin/namecore,bitcoin/bitcoin,anditto/bitcoin,kallewoof/bitcoin,anditto/bitcoin,particl/particl-core,kallewoof/bitcoin,andreaskern/bitcoin,bitcoin/bitcoin,kallewoof/bitcoin,tecnovert/particl-core,andreaskern/bitcoin,fujicoin/fujicoin,GroestlCoin/GroestlCoin,sstone/bitcoin,ajtowns/bitcoin,bitcoin/bitcoin,andreaskern/bitcoin,lateminer/bitcoin,sipsorcery/bitcoin,GroestlCoin/GroestlCoin,GroestlCoin/bitcoin,sipsorcery/bitcoin,ajtowns/bitcoin,sipsorcery/bitcoin,jamesob/bitcoin,ajtowns/bitcoin,jamesob/bitcoin,bitcoinsSG/bitcoin,AkioNak/bitcoin,namecoin/namecoin-core,sstone/bitcoin,bitcoinsSG/bitcoin,tecnovert/particl-core,namecoin/namecore,domob1812/bitcoin,Xekyo/bitcoin,tecnovert/particl-core,AkioNak/bitcoin,GroestlCoin/bitcoin,bitcoinsSG/bitcoin,mruddy/bitcoin,bitcoin/bitcoin,GroestlCoin/GroestlCoin,GroestlCoin/bitcoin,instagibbs/bitcoin,sstone/bitcoin,jambolo/bitcoin,anditto/bitcoin,jamesob/bitcoin,mruddy/bitcoin,bitcoinsSG/bitcoin,GroestlCoin/bitcoin,fujicoin/fujicoin,sstone/bitcoin,bitcoin/bitcoin,GroestlCoin/bitcoin,anditto/bitcoin,instagibbs/bitcoin,namecoin/namecore,mruddy/bitcoin,particl/particl-core,lateminer/bitcoin,fanquake/bitcoin,tecnovert/particl-core,GroestlCoin/GroestlCoin,jambolo/bitcoin,instagibbs/bitcoin,Xekyo/bitcoin,AkioNak/bitcoin,namecoin/namecore,andreaskern/bitcoin,lateminer/bitcoin,sipsorcery/bitcoin,namecoin/namecoin-core,namecoin/namecore,bitcoinsSG/bitcoin,particl/particl-core,sipsorcery/bitcoin,jambolo/bitcoin,fanquake/bitcoin,ajtowns/bitcoin,andreaskern/bitcoin,GroestlCoin/GroestlCoin,sipsorcery/bitcoin,jambolo/bitcoin,jamesob/bitcoin,sstone/bitcoin,instagibbs/bitcoin,fujicoin/fujicoin,fujicoin/fujicoin,tecnovert/particl-core,Xekyo/bitcoin,namecoin/namecoin-core,jambolo/bitcoin,kallewoof/bitcoin,AkioNak/bitcoin,domob1812/bitcoin,particl/particl-core,particl/particl-core,lateminer/bitcoin,namecoin/namecoin-core,namecoin/namecore,mruddy/bitcoin,Xekyo/bitcoin,ajtowns/bitcoin,bitcoin/bitcoin,namecoin/namecoin-core,lateminer/bitcoin,bitcoinsSG/bitcoin,instagibbs/bitcoin