Clean up DexOptHelper.

1. Removed the check on "instant_app_dexopt_enabled": It was added by
   ag/2412782, with the goal being "enable/disable dexopt for instant
   apps remotely" via "gservices". "gservices" is a predecessor of P/H
   (go/android-gservices), and instant apps are being deprecated
   (go/aia-instantapps-deprecation-plan), so nobody cares about the
   switch now.
2. Removed the check on "recoverability_detection": The flag is always
   enabled since Android 15.
3. Removed the DexoptOptions parameter from shouldPerformDexopt and
   deferred the construction of DexoptOptions: shouldPerformDexopt no
   longer needs DexoptOptions since ag/27755957.
4. Renamed shouldPerformDexopt to shouldCallArtService and added
   comments to clarify its exact behavior.
5. Added shouldSkipDexopt: This is the new preferred way to skip dexopt.
6. Removed the out-of-date comments about the shouldPerformDexopt
   conditions. Those comments have been out of sync with the actual
   conditions for a long time. The actual conditions are
   self-explanatory enough, so we don't really need comments.
7. Removed the out-of-date comments about performing dexopt on the first
   time the instant app starts. The current code doesn't have such a
   behavior.

Bug: 377474232
Change-Id: I502823bcd53e0c52536afa86e78ac36428286c2f
Test: Presubmit
Flag: EXEMPT refactor