chore: postgres_driver.nim - rename table's name from "messages" to "message"

[Ivansete-status]

Description

Simple PR where we rename the Postgres table to a more idiomatic name for relational databases.

Issue

#1842

[github-actions]

This PR may contain changes to database schema of one of the drivers.

If you are introducing any changes to the schema, make sure the upgrade from the latest release to this change passes without any errors/issues.

Please make sure the label release-notes is added to make sure upgrade instructions properly highlight this change.

[github-actions]

You can find the image built from this PR at

quay.io/wakuorg/nwaku-pr:2110

Built from 548f6de

[gabrielmer]

Looks great! Thank you! :)

[NagyZoltanPeter]

It's fine, thank you.

[jakubgs]

As far as I can tell this broke shards.test fleet:

ERR 2023-10-06 07:29:39.164+00:00 4/7 Mounting protocols failed              topics="wakunode main" tid=1 file=wakunode2.nim:85 error="failed to setup archive driver: error creating table: error in createMessageTable: rowsRes is err in exec: error in rows: ERROR:  relation \"messageindex\" already exists\n"

Endless restart loop.

[jakubgs]

I have built 12e8b122 - which is the preiovus commit - here:
https://ci.infra.status.im/job/nim-waku/job/deploy-shards-test/14/

And it works:

admin@store-01.ac-cn-hongkong-c.shards.test:~ % d
CONTAINER ID   NAMES            IMAGE                              CREATED              STATUS
e2f30b5bbb7f   nim-waku-store   wakuorg/nwaku:deploy-shards-test   About a minute ago   Up About a minute (healthy)