Change string resource for face not detected error

Changes the face_acquired_not_detected error message to be a bit more
user friendly.

Fixes: b/136294142
Test: Manual build
Change-Id: Ic98122a55a73fa0bdf6761eb7c7985d9191d787f
diff --git a/core/res/res/values/strings.xml b/core/res/res/values/strings.xml
index 0c145a4..e265162 100644
--- a/core/res/res/values/strings.xml
+++ b/core/res/res/values/strings.xml
@@ -1538,7 +1538,7 @@
     <!-- Message shown during face acquisition when the user is not front facing the sensor [CHAR LIMIT=50] -->
     <string name="face_acquired_poor_gaze">Please look more directly at your device.</string>
     <!-- Message shown during face acquisition when the user is not detected [CHAR LIMIT=50] -->
-    <string name="face_acquired_not_detected">Can\u2019t see your face. Look at the phone.</string>
+    <string name="face_acquired_not_detected">Position your face directly in front of the phone.</string>
     <!-- Message shown during face acquisition when the device is not steady [CHAR LIMIT=50] -->
     <string name="face_acquired_too_much_motion">Too much motion. Hold phone steady.</string>
     <!-- Message shown during face acquisition when the sensor needs to be recalibrated [CHAR LIMIT=50] -->