devapp/owners: fix URL for GitHub team owners
devapp/owners: fix URL for GitHub team owners

The URL for GitHub teams doesn't follow the same github.com/{username}
pattern as for GitHub users (and organizations), so detect and handle
them separately.

Fixes golang/go#51322.

Change-Id: If766e0f6b075530f357f288003156fd9a89362c8
Reviewed-on: https://go-review.googlesource.com/c/build/+/387535
Trust: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
Run-TryBot: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Michael Pratt <e7f1edc6d5aa9f6c8c377425db8f1a5816cbbb88@google.com>

golang/build,golang/build,golang/build,golang/build