Closes #25761 #21603

When `text_edit` is not available we directly fallback to to `label`.
That means, when we have range to replace, we never use `insertText` and
only use it when we haven't found any range.

This PR fixes, this and uses `insertText` as fallback first, and then
`label`.

Release Notes:

- Fixed an issue where accepting LSP snippet completion would insert the
label instead of expanding the snippet.