fix SELENIUM_RESTORE_SPACE under qmk

[elelay]

On a rpi-2040 based ferris sweep (34 keys), #define SELENIUM_RESTORE_SPACE in config.h always converted backspace to space.
It should only do it when the other key for the same thumb is pressed.

I fixed it by removing the negation in keymap.c:

#   ifdef SELENIUM_RESTORE_SPACE
    if ((keycode & 0xff) == KC_BSPC &&
        thumb_mod_same_hand_as_space_held &&
        record->tap.count > 0
    ) {
        tap_code(KC_SPC);
        return false;
    }
#   endif

[elelay]

instead of !thumb_mod_same_hand_as_space_held