tests: net: socket: udp: Increase ztest stack size

The default ztest stack size was too small to run new UDP tests on
certain platforms (nrf52840 in this particular case), therefore increase
teh stack size in prj.conf.

(cherry picked from commit 429798c)

Original-Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>
GitOrigin-RevId: 429798c
Change-Id: I8b64c21d09fae2402a4bbb47074100502d0e2afd
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/5099021
Tested-by: Fabio Baltieri <fabiobaltieri@google.com>
Tested-by: ChromeOS Prod (Robot) <chromeos-ci-prod@chromeos-bot.iam.gserviceaccount.com>
Commit-Queue: Fabio Baltieri <fabiobaltieri@google.com>
Reviewed-by: Fabio Baltieri <fabiobaltieri@google.com>

tests/net/socket/udp/prj.conf

@@ -21,6 +21,7 @@ CONFIG_ETH_DRIVER=n
 CONFIG_TEST_RANDOM_GENERATOR=y
 
 CONFIG_MAIN_STACK_SIZE=2048
+CONFIG_ZTEST_STACK_SIZE=2048
 CONFIG_HEAP_MEM_POOL_SIZE=256
 
 CONFIG_ZTEST=y