Short answer: you don’t. If your looking for low effort healing then Whitemane simply has nothing for you. Being hard is just part of her thing. Especially with E build which is her hardest build to play.
Long answer: A lot of it comes down to just being more and more efficient. Even at level 1, a measly 45 can easily heal thousands. A vast majority of her healing is also only happening during fights which is when it actually matters unlike Lucio who will put out some impressive numbers but a lot of that healing is during times where no one is really in danger anyway.
Also, because whitemane has to do damage in order to heal she tends to deal a fair amount of damage in fights as well. There are times where I can keep up with my teams dps and occasionally even beat them.
If you want an even longer answer I’ve written a guide for her.