Shorten video playback time to meet CTS quality bar.

The quality bar expects the test to finish in less than 30 seconds.
Reduce audio/video playback time to 20 seconds.
The first ten seconds plays the clear lead, the next ten seconds
verifies encrypted playback.

Test: atest CtsMediaDrmTestCases:android.mediadrm.cts.NativeMediaDrmClearkeyTest#testClearKeyPlaybackCenc --iterations 20

Test: atest CtsMediaDrmTestCases:android.mediadrm.cts.NativeMediaDrmClearkeyTest#testClearKeyPlaybackCenc2 --iterations 20

Bug: 201630492
Bug: 201630603
Change-Id: I8b095e64719df8f4001ae61426d452982e5229a6
diff --git a/tests/tests/mediadrm/libmediadrmndkjni/native-mediadrm-jni.cpp b/tests/tests/mediadrm/libmediadrmndkjni/native-mediadrm-jni.cpp
index 6c700fc..0eca4fd 100644
--- a/tests/tests/mediadrm/libmediadrmndkjni/native-mediadrm-jni.cpp
+++ b/tests/tests/mediadrm/libmediadrmndkjni/native-mediadrm-jni.cpp
@@ -62,7 +62,10 @@
 
 static const char kFileScheme[] = "file://";
 static constexpr size_t kFileSchemeStrLen = sizeof(kFileScheme) - 1;
-static constexpr size_t kPlayTimeSeconds = 30;
+// Test time must be under 30 seconds to meet CTS quality bar.
+// The first ten seconds in kPlayTimeSeconds plays the clear lead,
+// the next ten seconds verifies encrypted playback.
+static constexpr size_t kPlayTimeSeconds = 20;
 static constexpr size_t kUuidSize = 16;
 
 static const uint8_t kClearKeyUuid[kUuidSize] = {