rust: Drop oeqa-selftest-Increase-timeout-in-process-sigpipe-ru.patch

rust: Drop oeqa-selftest-Increase-timeout-in-process-sigpipe-ru.patch

This patch was originally added to address a rare failure on the PPC
target observed in AB. Currently, we are no longer testing the PPC
target in OE-Core. Therefore, we can remove this local patch. We have
also verified PPC testing locally several times without this patch,
and the issue has not reoccurred.

Signed-off-by: Deepesh Varatharajan <Deepesh.Varatharajan@windriver.com>
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>