Prior to this commit, the `"client.name"` key value for the
`"http.client.requests"` client HTTP observations would be considered as
high cardinality, as the URI host is technically unbounded.
In practice, the number of hosts used by a client in a given application
can be considered as low cardinality. This commit moves this keyvalue to
low cardinality so that it's present for both metrics and traces.
Closes gh-29839
767f59a3ae