When an ad is inserted into a live period with an unset
duration, the live period needs to be wrapped with a
`ClippingMediaPeriod` and then actually be clipped to
the end position when the duration gets known. Without
this the renderers will never see an EOS which prevents
the reading/playing period from advancing.
In the case of a server side inserted ad on the other
hand, the actual clipping needs to be prevented to
keep the current behavior for SSAI streams. In an SSAI
stream, an ad inserted before the current position should
not produce a snap back to the newly inserted ad. This is
currently prevented in both places, when the updated
timeline is handled to not disable the renderers, and when
the `mediaPeriodQueue` updates the queued periods. This
behaviour is preserved to not create side effects of this
change.
PiperOrigin-RevId: 742642715
c95544156d