Don't write license data to Android-${TARGET_PRODUCT}.mk

All the necessary license data is already propagated through the license
metadata file, and the entries in Android-${TARGET_PRODUCT}.mk are not
used.  Remove them, which should both reduce the size and parsing cost
of the Android-${TARGET_PRODUCT}.mk file and also removes a variable
that changes when dependencies are added or removed, which will
eventually allow running kati less often.

Bug: 309006256
Test: No change to out/Android-aosp_cf_x86_64_phone.ninja
Change-Id: Idfeb6fd10d77497ca274f8e74fe8e994ce1cafe6