fix(postgresql_metrics source): Support PG17

[biggerfisch]

Summary

Fixes the postgresql_metrics source to support PostgreSQL 17.

In PG17, several metric values were moved from pg_stat_bgwriter to a new view,
pg_stat_checkpointer. This caused the existing queries here that feed the metrics to break, as
they relied on those columns being present.

To fix this, the source now inspects the version of the server and dynamically decides what metrics
to expect and what views may be queried for them.

Since the metric names include the name of the view they were sourced from, this does mean that
after this change ships, a user upgrading to PG 17 from a lower version would see some metrics
disappear and similar ones appear. However, without this change, no new metrics would appear (and
indeed, all of the pg_stat_bgwriter metrics would disappear), so this is not a net behavior
regression IMHO.

Vector configuration

Did not test outside of integration testing yet at this time.

How did you test this PR?

Updated integration tests to test against PostgreSQL versions 13.1 (the existing test setup) and
17.5 (the latest version that should now be supported). The updated tests consider the version under
test and expect different metrics to be present based on the version.

Did not test outside of integration testing yet at this time.

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

References

Closes: #22094

Notes

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[biggerfisch]

Hi @vectordotdev/vector - is this something that can be reviewed? TYVM!

[pront]

Thanks!

[thomasqueirozb]

Hi @biggerfisch, this branch now has some merge conflicts and it seems like you didn't allow pushes to your fork, therefore I cannot fix them. Please fix these and then we can merge, thanks!