Revert Marketing KPI's on Index Page to Original Set
Hi @sytses, please review and merge.
Reverted !25276 (merged) to show original marketing KPI's prior to any changes or replacements.
Preserved some of the updated definitions from Mktg team and handbook links where possible.
Note that LTV/CAC had been included under Sales because the definition existed already w/in the Sales handbook, but this has been reverted as a part of this MR as well, to sit within Mktg as originally intended.
@darawarde could your team please submit new MR's that spell out the intended go-forward approach for each existing KPI w/ @sytses and @twbarr assigned to ensure transparency and Sid's approval? Happy to help with this too if you would like to set up some time to accomplish quickly.