fix: spans should only include path in http.route (backport #7390)

[carodewig]

Per the OpenTelemetry spec, the http.route should only include "the matched route, that is, the path template used in the format used by the respective server framework."

The router currently sends the full URI in http.route, which can be high cardinality (ie /graphql?operation=one_of_many_values). After this change, the router will only include the path (/graphql).

In order to test this, I added a dependency on tracing-mock. It's currently in beta, but it's already used within the tracing library itself so I think it's probably pretty stable. However I'm happy to come up with another way to test this if preferred.

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Notes

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This is an automatic backport of pull request #7390 done by [Mergify](https://mergify.com).

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[carodewig]

tracing-mock requires a more modern version of tracing than we have in 1.x, so the tests as written don't work.
Ideally, I'd like to wait for the backport of #7369 which will allow us to easily test the attributes on spans.