runtime: define the AddrRange used for testing in terms of addrRange

Currently the AddrRange used for testing is defined separately from
addrRange in the runtime, making it difficult to test it as well as
addrRanges. Redefine AddrRange in terms of addrRange instead.

For #40191.

Change-Id: I3aa5b8df3e4c9a3c494b46ab802dd574b2488141
Reviewed-on: https://go-review.googlesource.com/c/go/+/242677


Trust: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Austin Clements <austin@google.com>