luci-proto-wireguard: fix loading peer descriptions

Explicitly load `network` uci in wireguard rpcd backend as `ctx.foreach()`
does not implicitly load it.

Also remove leftover test setup information from the status page source.

Fixes: #6095
Fixes: 008fa188 ("luci-proto-wireguard: rewrite rpcd handler in ucode")
Fixes: 6e6fce3e

 ("luci-proto-wireguard: merge status page functionality")
Ref: https://github.com/jow-/ucode/pull/126
Signed-off-by: Jo-Philipp Wich <jo@mein.io>