Fix sharesheet timeout by sending CreatePredictionSession request immediately...

Fix sharesheet timeout by sending CreatePredictionSession request immediately instead of pushing it to the main thread Looper queue. CreatePredictionSession request is latency-sensitive.Its sendImmediately flag was flipped to be false accidentally in I937cdaa6081d2b85d27ee0192f6af7f197b8e102.

Bug: 195411307
Test: atest CtsSharesheetTestCases:android.sharesheet.cts.CtsSharesheetDeviceTest
Test: manually test on the device
Change-Id: If7d3f7acadcbed3340616b0ab239c776dedf7af7