### Why are the changes needed?
For my use case, the instances are not human readable, so I prefer to return the FQDN.
<img width="1483" alt="image" src="https://github.com/user-attachments/assets/92045517-456f-4087-8a36-9e3e4bea2f1d" />
### How was this patch tested?
Integration testing.
```
(base) ➜ dist git:(prometheus_label_2) cat conf/kyuubi-defaults.conf
kyuubi.metrics.prometheus.metrics.instance.enabled=true
kyuubi.zookeeper.embedded.client.port.address=localhost
kyuubi.frontend.bind.host=localhost
```
<img width="1692" alt="image" src="https://github.com/user-attachments/assets/0b60d504-62ec-418d-880b-f8a2f00d5550" />
### Was this patch authored or co-authored using generative AI tooling?
No.
Closes#6864 from turboFei/prometheus_label_2.
Closes#6864
d24571ccb [Wang, Fei] match
6a6a5110b [Wang, Fei] comments
c3046d4a1 [Wang, Fei] save
fb2021a31 [Wang, Fei] revert
42395945e [Wang, Fei] compatible
17b7007f5 [Wang, Fei] add instance label
Authored-by: Wang, Fei <fwang12@ebay.com>
Signed-off-by: Cheng Pan <chengpan@apache.org>
aa33521cf7