tests: net: socket: Increase ztest stack size for offload_dispatcher

The test suite is failing on qemu_cotext_a9 due to stack overflow.
Apparently this issue can also be observed on main after enabling
STACK_SENTINEL, however the test only started crashing after TCP
changes.

Signed-off-by: Robert Lubos <[email protected]>

Author: rlubos

tests/net/socket/offload_dispatcher/prj.conf

@@ -1,5 +1,6 @@
 CONFIG_NET_TEST=y
 CONFIG_ZTEST=y
+CONFIG_ZTEST_STACK_SIZE=2048
 
 # Networking config
 CONFIG_NETWORKING=y