What are these protuberances on the north edge of runway 10/28 at Mataveri?
It isn't a change in the runway length.* It was last lengthened in the 80s to serve as a Space Shuttle emergency landing site (latimes.com), and the length hasn't changed since.
Between c. 2007 and 2011 (sorry clouds got in the way) the runway was resurfaced in stages. In one stage, the runway was shortened and given a temporary (small; cheap) turnaround pad (with centerline markings as well). When this happens, the declared distances are amended.
When the work was done, a new proper one was built, and the temporary small one became vestigial. Note the X marking in the second image, and note that many runways utilize mid-runway turnaround pads to shorten the taxi time back to the terminal (on the west end).
* well, in a sense, it was