`supportsTracing` does not support side-by-side installs of core-tracing

[maorleger]

Suppose @azure/identity pins @azure/core-tracing to 1.0.0, but @azure/test-utils floats it at ^1.0.0 as an example).

In that case, supportsTracing will set the instrumenter at @azure/[email protected], but identity will use @azure/[email protected] and the tests will fail.

In production, at least in node, this is not an issue because of how OTel wires up the plugin (using require-in-the-middle).

But for tests we should find a way to support side-by-side versions of core-tracing in the supportsTracing test helper.