Don't enable jdwp by default on userdebug builds

We would like to have userdebug builds as close to user builds as
possible so don't enable jdwp by default on userdebug builds. This
means that we won't be able to attach a debugger to non-debuggable
builds in userdebug builds by default. However, this support can
be enabled by setting persist.debuggable.dalvik.vm.jdwp.enabled
property. Eng builds still enable jdwp by default.

Bug: 240410400
Test: System boots
Change-Id: Iad52254be9b9bc8c9deac8b3ad46e9db1b610160