transcoding: statically link libmediatranscoding.so in tests

Otherwise test doesn't work after service moved to apex.

bug: 173627260
bug: 159172726
test:
With local changes to move service to apex,
atest TranscodingSessionController_tests
Should not see link error in test.

Change-Id: I4729cb5ee1635a8143fb803b22a20e3c59ce378c
diff --git a/media/libmediatranscoding/Android.bp b/media/libmediatranscoding/Android.bp
index 735afc2..1934820 100644
--- a/media/libmediatranscoding/Android.bp
+++ b/media/libmediatranscoding/Android.bp
@@ -48,7 +48,7 @@
     },
 }
 
-cc_library_shared {
+cc_library {
     name: "libmediatranscoding",
 
     srcs: [