tests: net: tcp2: Fix crash in frdm_k64f

Lowering the connection timeout in order to avoid spin lock assert
in frdm_k64f device. This error was seen with this device

ASSERTION FAIL [z_spin_lock_valid(l)] @ zephyr/include/spinlock.h:92
        Recursive spinlock 0x20003590

Fixes #28602

Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>