Fix install_demo_configuration.sh script
- removed references to search guard & elastic search
- updated url used to download ctl (but looks like it hasn't been published yet)
- fixed detection of open search version
I pushed it to the main branch by mistake
Closes https://git.eliatra.com/eliatra-suite/eliatra-opensearch-plugin/-/issues/95
Edited by Kacper Trochimiak