chore(nifi): Bump to 2.2.0

[dervoeti]

Part of stackabletech/nifi-operator#740

Summary of changes:

• NiFi bumped to 2.2.0, this introduced breaking changes, since it's the bump from NiFi 1 to NiFi 2
• Support for templates was removed in NiFi 2. To make our demos work, we now use flow versioning via the integrated GitHubFlowRegistryClient in NiFi 2.
• The Python scripts were modified to register the GitHubFlowRegistryClient in NiFi and restore the flows of the specific demo
• I manually converted the templates to NiFi compatible JSON definition of the contained flows. This included porting some processors from NiFi 1 to NiFi 2, e.g. replace PublishKafka_2_6 by PublishKafka, because PublishKafka_2_6 was removed. I did this by exporting the flow definition from NiFi 1, importing them into NiFi 2 and then manually replacing all processors with their NiFi 2 versions (and reconfiguring them if needed).

The branch from which the flows are restored is hardcoded, which is not ideal, but I have no good idea yet on how to make this dynamic. It must be changed if something in the .json dumps of the process groups is changed, which should rarely happen, so it's likely not a huge problem.

[razvan]

not a full review. I was just curious.

[dervoeti]

This is ready for review now. A few things won't work in the demos, but this is related to MinIO TLS and the Waterlevel demo has a bug in the Superset measurements_per_day dataset. I'll fix both things in separate PRs. All the NiFi related stuff should work.

The current state of the code is laid out to pull the NiFi flows from the release-25.3 branch of this repo, which does not exist yet. To test it in the current state, replace all occurences of release-25.3 with bump/nifi-2.2.0-git-registry-client

[razvan]

The current state of the code is laid out to pull the NiFi flows from the release-25.3 branch of this repo, which does not exist yet. To test it in the current state, replace all occurences of release-25.3 with bump/nifi-2.2.0-git-registry-client

How about using "main" instead if "release-25.3" ? This would at least align the flows with the rest of the manifest paths, that we always update in the release branches anyway?

[dervoeti]

How about using "main" instead if "release-25.3" ? This would at least align the flows with the rest of the manifest paths, that we always update in the release branches anyway?

Yeah, I changed it to "main" now

[razvan]

Works, thanks!