Previous bugfix at 49f63b2 only partially fixed pagination host validation error.
Before this fix it was:
```
unexpected nextLink host \"management.azure.com\", expecting \"https://management.azure.com\"
```
Now we only check the `Host` without schema.
However, when Azure respond `nextLink` in `Host:Port` format, the
`nextLink` check will fail:
```
unexpected nextLink host \"management.azure.com:443\", expecting \"management.azure.com\"
```
This pull request further relaxes the checks by only checking the
`Hostname`.
---
related issue: https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6912
* lib/promscrape/discovery/azure: remove API server from URL returned by azure
* lib/promscrape/discovery/azure: validate nextLink contains same URL as apiServer
