Remove all usage of V2 terminology in the codebase and refactor to consolidate all logic with v1

[lumtis]

Will depend on completing #2402

To simplify transition period from protocol contracts v1 -> v2, we mention all new changes to integrate the new design as v2, this simplify the development process.

After implementation and full migration to the new design, this terminology should no longer be necessary.
Example: ProcessV2Deposit will simply becomes ProcessDeposit

We should also rename all v2 E2E tests as now the canonical tests and remove previous tests.