As you have correctly mentioned, manuscripts with major revisions are usually sent for a second round of review. However, the decision to send the paper for review lies completely with the editor. If the editor does not feel the need to send it for review once again, and if he/she feels equipped to take a decision without a review, it might not be sent for a second round of review. I don't think this indicates rejection because, as you have mentioned, the status almost immediately changed to "Awaiting final decision." It would have taken the editor some time to go through the revised paper to decide whether to accept or reject it. In fact, it is possible that the editor or a member of the editorial board has expertise on this topic and, therefore, they have decided to go ahead with an internal review rather than an external review.
- Will my paper be accepted if I make the revisions suggested?
- Does a quick second round of peer review indicate rejection?