[refactor] virtual pool gets generate at the beginning of each swap #check-lint-warning

Currently, the derived virtual pools get generated at the beginning of each block. To ensure price manipulation between swaps of a single block, we should calculate the virtual pools on every swap we make with them. This change does just that. No logic changes, just call the func that generates the virtual pool pre-swap.

Code Walkthrough https://www.youtube.com/watch?v=Wke82WgK8Ao