chore(benchmark): add warning for probably low memory

[kisvegabor]

fixes #5654

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[FASTSHIFT]

We may need to consider reducing some memory usage, because the 128K memory pool may not be available on most microcontrollers.
I checked and it was caused by the container_with_scrolling_cb function calling card_create 50 times to create 50 widgets.
Can we reduce the number of widgets, like 25? Or do we choose the number of widgets based on the size of the screen?

[kisvegabor]

I checked and it was caused by the container_with_scrolling_cb function calling card_create 50 times to create 50 widgets.
Can we reduce the number of widgets, like 25? Or do we choose the number of widgets based on the size of the screen?

It's fixed 50 to test the performance with many widgets. If we reduced it to 25 we were beat the purpose of the test.