Clean up existing build folders in repo and update .gitignore files
#8116
| Job | Run time |
|---|---|
| 1m 20s | |
| 3m 33s | |
| 12s | |
| 7s | |
| 6m 10s | |
| 2m 33s | |
| 2m 19s | |
| 59s | |
| 7m 7s | |
| 5m 16s | |
| 3m 32s | |
| 1m 56s | |
| 35m 4s |