[Confluence] update_or_create doesn't respect parent_id

[amirgon]

update_or_create calls page_exists and get_page_id regardless of the parent_id argument that was specified.
These in turn search for a page according to "title" anywhere in the space.

When "title" already appears (on a different hierarchy), update_or_create finds the "title" on the space, instead of the title under the specified parent_id.

As a result, when a title exists as a child of another page, it would be overwritten and moved to another parent instead of creating a new page or returning some error.