Fix SIGINT handler to modify the number of remaining training steps.

[justinxzhao]

• First SIGINT will try to finish training at the very next training step.
• Another SIGINT will stop training abruptly.

Also, removes quit_training -- this is no longer called anywhere.

[github-actions]

Unit Test Results

       6 files  ±  0         6 suites  ±0   1h 43m 16s ⏱️ + 12m 1s
2 785 tests +  9  2 750 ✔️ +  9    35 💤 ±0  0 ❌ ±0 
8 355 runs  +27  8 245 ✔️ +27  110 💤 ±0  0 ❌ ±0 

Results for commit 3250897. ± Comparison against base commit c3e4abf.

♻️ This comment has been updated with latest results.

[connor-mccorm]

Looks good to me, only thing I would maybe add is possibly initializing self.total_steps in the constructor if were switching to using the class variable. WDYT?

[justinxzhao]

Looks good to me, only thing I would maybe add is possibly initializing self.total_steps in the constructor if were switching to using the class variable. WDYT?

Good idea. Done!