feat: Include Spark connect in stacklet list

[sbernauer]

This also uncovered two bugs:

1. spark-connect-controller does not watch StatefulSets here
2. The label selectors app.kubernetes.io/name=spark-connect,app.kubernetes.io/instance=spark-connect und app.kubernetes.io/name=spark-history,app.kubernetes.io/instance=spark-history match nothing. We should set app.kubernetes.io/name=spark-connect instead of currently app.kubernetes.io/name: spark-k8s (same for HistoryServer)

I pinged @razvan about the bugs, once they are fixed everything should work
=> He created stackabletech/spark-k8s-operator#573

┌───────────────┬───────────────┬───────────┬──────────────────────────────────────────────────────────────┬─────────────────────────────────┐
│ PRODUCT       ┆ NAME          ┆ NAMESPACE ┆ ENDPOINTS                                                    ┆ CONDITIONS                      │
╞═══════════════╪═══════════════╪═══════════╪══════════════════════════════════════════════════════════════╪═════════════════════════════════╡
│ hdfs          ┆ hdfs          ┆ default   ┆ datanode-default-0-listener-data     172.18.0.2:31278        ┆ Available, Reconciling, Running │
│               ┆               ┆           ┆ datanode-default-0-listener-http     http://172.18.0.2:32716 ┆                                 │
│               ┆               ┆           ┆ datanode-default-0-listener-ipc      172.18.0.2:32057        ┆                                 │
│               ┆               ┆           ┆ datanode-default-0-listener-metrics  172.18.0.2:31053        ┆                                 │
│               ┆               ┆           ┆ namenode-default-0-http              http://172.18.0.2:31589 ┆                                 │
│               ┆               ┆           ┆ namenode-default-0-metrics           172.18.0.2:31089        ┆                                 │
│               ┆               ┆           ┆ namenode-default-0-rpc               172.18.0.2:31233        ┆                                 │
│               ┆               ┆           ┆ namenode-default-1-http              http://172.18.0.2:31372 ┆                                 │
│               ┆               ┆           ┆ namenode-default-1-metrics           172.18.0.2:31917        ┆                                 │
│               ┆               ┆           ┆ namenode-default-1-rpc               172.18.0.2:31921        ┆                                 │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ spark-connect ┆ spark-connect ┆ default   ┆                                                              ┆ Available, Reconciling, Running │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ zookeeper     ┆ zookeeper     ┆ default   ┆                                                              ┆ Available, Reconciling, Running │
└───────────────┴───────────────┴───────────┴──────────────────────────────────────────────────────────────┴─────────────────────────────────┘

Definition of Done Checklist

• Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant
• Please make sure all these things are done and tick the boxes

# Author
- [ ] Changes are OpenShift compatible
- [ ] CRD changes approved
- [ ] Helm chart can be installed and deployed operator works
- [ ] Integration tests passed (for non trivial changes)

# Reviewer
- [ ] Code contains useful comments
- [ ] (Integration-)Test cases added
- [ ] Documentation added or updated
- [ ] Changelog updated
- [ ] Cargo.toml only contains references to git tags (not specific commits or branches)

# Acceptance
- [ ] Feature Tracker has been updated
- [ ] Proper release label has been added

[maltesander]

LGTM!