selftests: rds: Increase selftest timeout

The 400s time out was originally developed under a leaner
kernel config that booted much faster than a default config.
Boot up is included as part of the over all test runtime, as
well as any log collection done when the test is complete.
A slower config combined with the gcov enabled test means
we'll need more time to accommodate the boot up and log
collection.  So, bump time out to 800s.

Signed-off-by: Allison Henderson <achender@kernel.org>
Link: https://patch.msgid.link/20260504054143.4027538-2-achender@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/rds/settings

@@ -1 +1 @@
-timeout=400
+timeout=800