[SR] Simplify memory re-use algorithm (#68302)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68302
Implement the new memory re-use algorithm. It’s roughly based on the c2 one, but after going through many iterations it may not be a 1:1 port anymore. Also deleted the old liveness analysis.
Test Plan:
## **Re-use metrics**
`inline_cvr` (294738512_58)
**Before**
* `local`
```
Total number of managed tensors: 2660
Total number of managed output tensors: 0
Total number of unmanaged values: 3041
Total memory managed: 4601984 bytes
Total number of reused tensors: 1183
```
* `local_ro`
```
Total number of managed tensors: 1412
Total number of managed output tensors: 0
Total number of unmanaged values: 2677
Total memory managed: 29696 bytes
Total number of reused tensors: 959
```
**After**
* `local`
```
Total number of managed tensors: 2660
Total number of managed output tensors: 0
Total number of unmanaged values: 3041
Total memory managed: 4520000 bytes
Total number of reused tensors: 1198
```
* `local_ro`
```
Total number of managed tensors: 1412
Total number of managed output tensors: 0
Total number of unmanaged values: 2677
Total memory managed: 29120 bytes
Total number of reused tensors: 963
```
Reviewed By: hlu1
Differential Revision: D32370424
fbshipit-source-id: 06a8e0a295ed7a2b4d14071349c1f1e975f746bf
