[AIR] Set name of Trainable to match with Trainer

[amogkam]

Before

Result logdir: /Users/amog/ray_results/train_func_2022-04-04_13-15-28
Number of trials: 1/1 (1 TERMINATED)
+------------------------+------------+-----------------+--------+------------------+----------+--------------+---------------------+
| Trial name             | status     | loc             |   iter |   total time (s) |     loss |   _timestamp |   _time_this_iter_s |
|------------------------+------------+-----------------+--------+------------------+----------+--------------+---------------------|
| train_func_f84c8_00000 | TERMINATED | 127.0.0.1:15503 |      3 |          3.17087 | 0.300253 |   1649103335 |            0.099402 |
+------------------------+------------+-----------------+--------+------------------+----------+--------------+---------------------+

After

Result logdir: /Users/amog/ray_results/TorchTrainer_2022-04-04_13-19-32
Number of trials: 1/1 (1 TERMINATED)
+--------------------------+------------+-----------------+--------+------------------+----------+--------------+---------------------+
| Trial name               | status     | loc             |   iter |   total time (s) |     loss |   _timestamp |   _time_this_iter_s |
|--------------------------+------------+-----------------+--------+------------------+----------+--------------+---------------------|
| TorchTrainer_8a298_00000 | TERMINATED | 127.0.0.1:15624 |      3 |           3.3461 | 0.278467 |   1649103579 |            0.135264 |
+--------------------------+------------+-----------------+--------+------------------+----------+--------------+---------------------+

Why are these changes needed?

Related issue number

Checks

• I've run scripts/format.sh to lint the changes in this PR.
• I've included any doc changes needed for https://docs.ray.io/en/master/.
• I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failures at https://flakey-tests.ray.io/
• Testing Strategy
  • Unit tests
  • Release tests
  • This PR is not tested :(