Do not create a TextClassificationSession if we are not going to use it. am: c94b3450ca am: 19df97df2f

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/libtextclassifier/+/11734845

Change-Id: I8ddc1e4aa43d125d6bb70217caaf626237a92f16