Closes https://github.com/neondatabase/neon/issues/1984
Closes https://github.com/neondatabase/neon/pull/2830
A follow-up of https://github.com/neondatabase/neon/pull/2830, I've
noticed that benchmarks failed again due to out of space issues.
Removes most of the pageserver and safekeeper files from disk after
every pytest suite run.
```
$ poetry run pytest -vvsk "test_tenant_redownloads_truncated_file_on_startup[local_fs]"
# ...
$ du -h test_output/test_tenant_redownloads_truncated_file_on_startup\[local_fs\]
# ...
104K test_output/test_tenant_redownloads_truncated_file_on_startup[local_fs]
$ poetry run pytest -vvsk "test_tenant_redownloads_truncated_file_on_startup[local_fs]" --preserve-database-files
# ...
$ du -h test_output/test_tenant_redownloads_truncated_file_on_startup\[local_fs\]
# ...
123M test_output/test_tenant_redownloads_truncated_file_on_startup[local_fs]
```
Co-authored-by: Bojan Serafimov <bojan.serafimov7@gmail.com>
