Work around incorrect R8 proguard compatibility

Proguard treats -dontobfuscate -keepattributes *Annotations* the
same as -dontobufscate by keeping all attributes.  R8, even in
proguard compatibility mode, discards all attributes that don't
match, including EnclosingClass attributes that may be necessary.
Pass -keepattributes * whenever passing -dontobfuscate to make R8
act more like proguard.

This isn't a complete solution, some modules may set
LOCAL_PROGUARD_ENABLED := custom and then manually specify
-dontobfuscate on the command line or in a flags file, in which
case they will see the incorrect behavior of R8.

Bug: 80081393
Test: m checkbuild
Test: examine attributes on com.android.stk.BootCompletedReceiver
      in out/target/common/obj/APPS/Stk_intermediates/classes.dex

Change-Id: I761f2d0617c5295df8fc7adfc4fd00d2aa41961e