Collect column stats using helper on Postgres < 17 despite warning

[seanlinsley]

Followup to #610, this makes it so we only fall back to querying pg_stats directly on Postgres 17 and older, since the old function definition will still work until the database server is upgraded.

[keiko713]

Change makes sense, but I don't see the context much. Was this discussed in #610? Or got some feedback somewhere else?

[seanlinsley]

No one's reported it, it was just an improvement I thought up. In the case there would be a permissions error when querying pg_stats directly on old Postgres versions, this will allow the collector to still collect column stats until they upgrade to Postgres 17.

[keiko713]

Ah nice, thanks for the additional context 👍