[v0.14.0.x] Fix off-by-one error in InstantSend mining info removal when disconnecting blocks#2951

UdjinM6 merged 2 commits intodashpay:v0.14.0.xdashpay/dash:v0.14.0.xfrom

codablock:pr_is_removeislockminedcodablock/dash:pr_is_removeislockminedCopy head branch name to clipboard