SDK / exoplayer

Removing this method requires custom MediaSource implementations to switch
to the new version. While this breaks the implmentation, it also avoids problems
with accidentely forwarding to the wrong method or with accidental stack
overflows when none of the two methods gets implemented.

It's unlikely any callers are affected because this is only the extended version
with the defaultProjectionPositionUs parameter that no caller except the
internal player will use.

PiperOrigin-RevId: 267323042