Revert^4 "CalendarTests minsdk  bump from 19 to 21"

222073fa50e293f3fdde3a5d3527e0a4c2a1d762

Change-Id: Ie3129c6b2209011672727e792cb45b1be94b481e
Merged-In: Ia2f80a011daaf4921032538dea98627c83d30843

tests/Android.bp

diff --git a/tests/Android.bp b/tests/Android.bp
index bcb56ab..1312a25 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -32,7 +32,7 @@
         "android-common",
         "androidx.test.rules",
     ],
-    sdk_version: "19",
+    sdk_version: "21",
     // Test needed artifacts
     data: [
         ":Calendar",