shortcode executed in the page editor

From the add_shortcode() docs:

Note that the function called by the shortcode should never produce an output of any kind. Shortcode functions should return the text that is to be used to replace the shortcode. Producing the output directly will lead to unexpected results.

Your code should be:

function vbshort_shortcode() {
    return 'Hello shotcode!';
}

add_shortcode('vbshort', 'vbshort_shortcode');