packages/services/Telecomm: Set LOCAL_SDK_VERSION where possible.

This change sets LOCAL_SDK_VERSION for all packages where
this is possible without breaking the build, and
LOCAL_PRIVATE_PLATFORM_APIS := true otherwise.

Setting one of these two will be made required soon, and this
is a change in preparation for that. Not setting LOCAL_SDK_VERSION
makes the app implicitly depend on the bootclasspath, which is
often not required. This change effectively makes depending on
private apis opt-in rather than opt-out.

Test: make relevant packages
Bug: 73535841
Change-Id: I44cbcaef285632fc8471c050e69678eab6f3968f
diff --git a/testapps/Android.mk b/testapps/Android.mk
index 74928d0..b600dca 100644
--- a/testapps/Android.mk
+++ b/testapps/Android.mk
@@ -25,6 +25,7 @@
 LOCAL_SRC_FILES := $(call all-java-files-under, src)
 
 LOCAL_PACKAGE_NAME := TelecomTestApps
+LOCAL_PRIVATE_PLATFORM_APIS := true
 LOCAL_CERTIFICATE := platform
 
 LOCAL_MODULE_TAGS := tests