Increase IME sharding.

Currently:
- Shard 1 takes 16min
- Shard 2 takes 26min

Both shards need to be within 20min, so splitting shard2 into shard2 and shard3 with 8min each

Test: atest FlickerTestsIme
Fixes: 352263780
Change-Id: Iee133322cced7ed8e486e749ef49d70e51b95761