[automerge] Rename Encoder test names. 2p: 0c1f32bfa2

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/libtextclassifier/+/17392093

Bug: 226182044
Change-Id: Idb3694acf3fa86e08ff02764a466042d212d0acd