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/AndroidManifest.xml b/AndroidManifest.xml
index eb91b81..8b4ef03 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -18,7 +18,7 @@
     package="com.android.messaging"
     android:installLocation="internalOnly">
 
-    <uses-sdk android:minSdkVersion="19" android:targetSdkVersion="28" />
+    <uses-sdk android:minSdkVersion="19" android:targetSdkVersion="24" />
 
     <!-- Application holds CPU wakelock while working in background -->
     <uses-permission android:name="android.permission.WAKE_LOCK" />