OTEL span identification breaks on external spans

**Describe the bug**
I wanted to make sure that it wasn't a me-issue, so I invested untold amounts of time making sure of this.
I've instrumented two services that talk with each other through http and trying to play matchup is annoying so I ofc just forwarded a `b3` header between them to connect the spans into a single transaction.
Once connected, APM loses the capability of identifying anything regarding the spans beyond their associability and errors.
Easier to see to understand
Trace from Client, nice and pretty:
Trace from Server, so much detail, how lovely:

Connected. All the information is gone:

This is not just the coloring, it's the tagging, it's the name subheader thing for requests, it's the chips tagging the transaction:

and other such things. Also, why does it say `GET http:`? it's supposed to say `GET`. or at least pull the `url.route` or something.

This also reminds me , shoving the entire fully-fledged url there like it sometimes does is really unhelpful. Something tagged with `GET https://my.subdomain.cloudinsatnce-hash.com/path/group/fa2c8bc2-361a-427f-beed-aa2f0ae15a8e/entity/3bc8e74e-d831-4172-8196-08da6fc228a2?param1=1¶m2=2¶m3=jfdkl&longParam=fjjkdaohfonsaohvunklareiahfjdlsghudaflscjnauehgjkdajhjjahifhjsk` might as well be untagged at all 🤔

There is no literature at all regarding anything otel in apm besides a "we have partial native support" statement so I might be missing something that is not written anywhere..

**To Reproduce**
Steps to reproduce the behavior:
1. connect any two traces from different resources
2. Information gone

**Expected behavior**
Information not-gone, or at least not **completely** scrubbed out

Start by reproducing the two-service trace connection described in the issue, forwarding the b3 header between services and comparing the resulting span details. Done means externally connected spans retain their identification, tags, request naming, transaction chips, and useful HTTP method or route information instead of being scrubbed.

Written by the indexing model from the issue text.