Update citus, PG and HammerDB default versions

[naisila]

Drafting this since we can wait for Citus 11.2 release and replace "main" branch references with "release-11.2"

[gledis69]

Yeahhhh, keeping these values constantly updated feels like a hassle. Might be worth to write a script to do a sweeping find and replace in the whole repo. bash/python should do

[SaitTalhaNisanci]

Not sure if it covers what you want to do, but there is already a script updating some versions here: https://github.com/citusdata/test-automation/tree/master/release

[naisila]

Yeap, I already used @SaitTalhaNisanci 's script to update most of the values, and also updated the script's description.