fix(db-postgres): skip migrations in development mode when using push

[janbuchar]

• Prevents payload migrate from executing migrations in development mode when using drizzle's push mode, avoiding conflicts between the two schema sync mechanisms
  • I have had conflicts happen when developers tried to run migrations in development mode with push mode in place - this made it look like there is some kind of a problem with the migrations themselves, which is not great DX
• Only affects drizzle adapters (postgres, sqlite, etc.) - MongoDB behavior unchanged
• Users can still run migrations in dev by setting push: false in their adapter config