Revert "AOSP/Messaging - update the Messaging version to target P (28) or higher. Fixed tests in messagingtests. All tests pass/work."

This reverts commit 9752cda535870642b26f4d754afe4575cc6b4f97.

Reason for revert: com.android.devicehealthchecks are failing https://sponge.corp.google.com/target?id=3b9a97f0-48bc-410d-94ce-0971c2f75361&target=com.android.devicehealthchecks&searchFor=&show=FAILED&sortBy=STATUS

Change-Id: I82d337b1d859083169ac6057b408f7e920f06609
diff --git a/tests/AndroidManifest.xml b/tests/AndroidManifest.xml
index 3ad7d8e..867d8e1 100644
--- a/tests/AndroidManifest.xml
+++ b/tests/AndroidManifest.xml
@@ -17,7 +17,7 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.android.messaging.test" >
 
-    <uses-sdk android:minSdkVersion="16" android:targetSdkVersion="28"/>
+    <uses-sdk android:minSdkVersion="16" android:targetSdkVersion="19"/>
 
     <application android:label="Messaging Tests" >
         <uses-library android:name="android.test.runner" />