Tooltip/popover - change the default value for `fallbackPlacements` (#32437)

Tooltip/popover - change the default value for `fallbackPlacements` (#32437)

The default Popper `fallbackPlacements` value is `[oppositePlacement]`.

- The default value was previously (in v4) `'flip'` that can be achieved by passing the single value in the array, like — `[oppositePlacement]`. Keeping `null` also sets the `fallbackPlacements` to `[oppositePlacement]` (Default value in Popper)
- It's better to have **clockwise** (`['top', 'right', 'bottom', 'left']`) fallback options so that tooltip/popover can be placed to another side even if the opposite placement doesn't fit.

Co-authored-by: XhmikosR <xhmikosr@gmail.com>