[utest][Kconfig] adjust RT_CONSOLEBUF_SIZE when utest is enabled

src/Kconfig

@@ -456,6 +456,7 @@ config RT_USING_CONSOLE
 if RT_USING_CONSOLE
     config RT_CONSOLEBUF_SIZE
         int "the buffer size for console log printf"
+        default 256 if RT_USING_UTEST
         default 128
 
     config RT_CONSOLE_DEVICE_NAME