Bump Discourse operator version to 0.0.43

This MR updated the Discourse operator and the Discourse image to v3.3.0.beta1

Release notes:

• https://meta.discourse.org/t/3-3-0-beta1-discourse-discover-opt-in-hot-topics-page-its-illegal-flag-reason-and-more/298236

Related MR:

• paas-tools/infrastructure-ci!23 (merged)
• Remove ref: 'workaround-for-docker-host-no-such-host-error' when paas-tools/infrastructure-ci!23 (merged) is merged.