Drop use_source_config_var from >=V module sdk snapshots

With https://r.android.com/3048855, use_source_config_var has become a
no-op for source vs prebuilt selection. This CL updates the module sdk
generation script to drop this property from V and above snapshots. For
backwards compatibility, this property will be kept in the generated
snapshots for T and U

Implementation Details:
This has implemented by introducting a new mode
`PreferHandling.USE_NO_PREFER_PROPERTY`. When this mode is selected, the
generated Android.bp will not contain `prefer: false`. This
differentiates it from `PreferHandling.None` which keeps the `prefer:
false`.

Test: Generated module sdk snapshot for Adservices. The Android.bp
corresponding to "next" looks like this: https://paste.googleplex.com/6505539983114240
Test: presbumits

Bug: 335721403
(cherry picked from https://android-review.googlesource.com/q/commit:d790ff73020bea233d68372aeb4bb4e9712d25b2)
Merged-In: Ibc28e7e6dfbd6b28c47be5f5c6a71ba2610872de
Change-Id: Ibc28e7e6dfbd6b28c47be5f5c6a71ba2610872de