audio policy: fix attributes for strategy "rerouting"

Strategy rerouting is used for audio injection to a recorder
dynamic audio policy mix. As such, the correponding audio attributes
must contain usage AUDIO_USAGE_VIRTUAL_SOURCE.

Bug: 162239551
Test: gts-tradefed run gts --skip-device-info -m GtsGmscoreHostTestCases -t 'com.google.android.gts.audioservice.AudioServiceHostTest#testInjectForRecord'
Change-Id: Id175b9583faf8910aef7b2988ac5019d0cbbcb53
(cherry picked from commit ed49c8644a89304cd5ae3056245a07d04a8911de)
diff --git a/services/audiopolicy/engine/common/src/EngineDefaultConfig.h b/services/audiopolicy/engine/common/src/EngineDefaultConfig.h
index 981582e..1821140 100644
--- a/services/audiopolicy/engine/common/src/EngineDefaultConfig.h
+++ b/services/audiopolicy/engine/common/src/EngineDefaultConfig.h
@@ -136,7 +136,7 @@
     {"rerouting",
      {
          {"", AUDIO_STREAM_REROUTING, "AUDIO_STREAM_REROUTING",
-          {{AUDIO_CONTENT_TYPE_UNKNOWN, AUDIO_USAGE_UNKNOWN, AUDIO_SOURCE_DEFAULT, 0, ""}}
+          {{AUDIO_CONTENT_TYPE_UNKNOWN, AUDIO_USAGE_VIRTUAL_SOURCE, AUDIO_SOURCE_DEFAULT, 0, ""}}
          }
      },
     },