Set correct `pg_distrib_dir` in `pageserver.toml` and in neon_local
`config`.
`test_forward_compatibility` shows flakiness during `neon_local pg
start`, so hopefully, the patch will help.
```
2022-11-15 16:07:34.091 GMT [13338] LOG: starting with zenith basebackup at LSN 0/A6A9310, prev 0/0
2022-11-15 16:07:34.091 GMT [13338] FATAL: cannot start in read-write mode from this base backup
2022-11-15 16:07:34.091 GMT [13337] LOG: startup process (PID 13338) exited with exit code 1
```
If there are any unexpected ERRORs or WARNs in pageserver.log after test
finishes, fail the test. This requires whitelisting the errors that *are*
expected in each test, and there's also a few common errors that are
printed by most tests, which are whitelisted in the fixture itself.
With this, we don't need the special abort() call in testing mode, when
compaction or GC fails. Those failures will print ERRORs to the logs,
which will be picked up by this new mechanisms.
A bunch of errors are currently whitelisted that we probably shouldn't
be emitting in the first place, but fixing those is out of scope for this
commit, so I just left FIXME comments on them.
Add `test_forward_compatibility`, which checks if it's going to
be possible to roll back a release to the previous version.
The test uses artifacts (Neon & Postgres binaries) from the previous
release to start Neon on the repo created by the current version. It
performs exactly the same checks as `test_backward_compatibility` does.
Single `ALLOW_BREAKING_CHANGES` env var got replaced by
`ALLOW_BACKWARD_COMPATIBILITY_BREAKAGE` &
`ALLOW_FORWARD_COMPATIBILITY_BREAKAGE` and can be set by `backward
compatibility breakage` and `forward compatibility breakage` labels
respectively.
This PR replaces the following global variables in the test framework
with fixtures to make tests more configurable. I mainly need this for
the forward compatibility tests (draft in
https://github.com/neondatabase/neon/pull/2766).
```
base_dir
neon_binpath
pg_distrib_dir
top_output_dir
default_pg_version (this one got replaced with a fixture named pg_version)
```
Also, this PR adds more `Path` type where the code implies it.
