Garbage and standing water benefit all mosquitoes against non-mosquito competitors. We only need to consider whether biting humans benefits human-biting mosquitoes over non-human-biting mosquitoes, or separately whether carrying malaria benefits malaria-carrying mosquitoes over non-malaria-carrying mosquitoes; eliminating either trait would be sufficient. I believe that neither of these are powerful enough, meaning that the malaria-carrying human-biting species can be almost seamlessly replaced by non-human-biting or non-malaria-carrying species with no risk of the trait re-evolving or of the broader ecological niche, as tiny and unimportant as it is, failing to be re-filled.

Is it that surprising? Populations of animals that depend on humans has generally expanded with people. This applies to livestock, pets, vermin etc.

Mosquitoes are prevalent even in super clean places, btw. I used to live by a small creek in Austin, TX and in the summers I could basically never enjoy my yard: it would be flooded by mosquitoes (the creek would have standing water which mosquitoes require to reproduce).