Bump AGP to 7.3.0 inside ReactAndroid (#34707)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/34707

AGP 7.3.0 just got released which is glorious!
This allows us to remove a lot of unnecessary boilerplate to handle correct task ordering
on both React Android & the template

Changelog:
[Android] [Changed] - Bump AGP to 7.3.0

Reviewed By: mdvacca

Differential Revision: D39553534

fbshipit-source-id: 9680893e9f48cac867206aeb7eb468dbf91c1643