tests: zbus: replacing K_NO_WAIT with K_FOREVER in integration tests

The zbus_chan_read with K_NO_WAIT was generating a fail in the
qemu_riscv32_smp board. This fix replaces the K_NO_WAIT with a K_FOREVER
on the test, which would not affect the test execution for other
platforms/boards.

Signed-off-by: Rodrigo Peixoto <rodrigopex@gmail.com>