test: move test-inspector-module to parallel

test-inspector-module is very fast and seems to be runnable at the same
time as other tests. Move from sequential directory to parallel.

PR-URL: #32025
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: Trott