Don't use AppsDefaultVersionName for framework-res.apk

Some builds set AppsDefaultVersionName() to include the build
number ("P-123456").  aapt2 copies the version name of
framework-res into app manifests as compileSdkVersionCodename,
which confuses things if it contains the build number.  Use the
DefaultAppTargetSdk ("P") instead.

Bug: 78324052
Test: m TARGET_BUILD_WITH_APPS_VERSION_NAME=true Dialer
      aapt dump badging $OUT/system/priv-app/Dialer/Dialer.apk | grep compile
      shows compileSdkVersionCodename=P
Change-Id: If67f40aae1066d4ff3bf97da1b2de2e1e250ad9c