WireMock.Minimal.Owin does not respect custom pathing for determining admin paths

[PeterBenko]

Describe the bug

All the code under WireMock.Minimal.Owin relies on hard-coded request.Path.StartsWith("/__admin/") for evaluation of admin paths, instead of respecting the customizable "WireMockServerSettings.AdminPath" entry.

This most noticably leads to admin requests getting logged (with isAdminRequest=false) and in OpenTelemetry tracing.

Expected behavior:

A consistent admin path behaviour.