Drop prebuilt files to android source tree.

CtsShim.apk
package: name=com.android.cts.ctsshim
versionCode=31
versionName=12-7471822
platformBuildVersionName=S
compileSdkVersion=31
compileSdkVersionCodename=S
sdkVersion:24
targetSdkVersion:28

CtsShimPriv.apk
package: name=com.android.cts.priv.ctsshim
versionCode=31
versionName=12-7471822
platformBuildVersionName=S
compileSdkVersion=31
compileSdkVersionCodename=S
sdkVersion:24
targetSdkVersion:28

CtsShim.apk
package: name=com.android.cts.ctsshim
versionCode=31
versionName=12-7471822
platformBuildVersionName=S
compileSdkVersion=31
compileSdkVersionCodename=S
sdkVersion:24
targetSdkVersion:28

CtsShimPriv.apk
package: name=com.android.cts.priv.ctsshim
versionCode=31
versionName=12-7471822
platformBuildVersionName=S
compileSdkVersion=31
compileSdkVersionCodename=S
sdkVersion:24
targetSdkVersion:28

Built here: ab/7471822

This build IS suitable for public release.

The change is generated with prebuilt drop tool.

Test: presubmit
Bug: 188062003
Change-Id: I96933aaefd72078263c127c8656fde2bd83606b7