MPD Patch does not work for multi-period MPDs

[tobbee]

A multi-period source like http://localhost:8888/livesim2/segtimeline_1/patch_60/periods_60/testpic_2s/Manifest.mpd does not result in proper patches.

This can be seen by asking for some specific MPDs and a Patch like:

curl http://localhost:8888/livesim2/segtimeline_1/patch_60/periods_60/testpic_2s/Manifest.mpd?publishTime=2024-04-21T06:10:58Z > 1.mpd
curl http://localhost:8888/livesim2/segtimeline_1/patch_60/periods_60/testpic_2s/Manifest.mpd?publishTime=2024-04-21T06:11:04Z > 2.mpd
curl http://localhost:8888/patch/livesim2/segtimeline_1/patch_60/periods_60/testpic_2s/Manifest.mpd\?publishTime\=2024-04-21T06:10:58Z&nowDate=2024-04-21T06:11:04Z > 1-2.mpp

The patch will remove the first Period, but the update of later period is not proper including addressing like

<replace sel="/MPD/Period[3]/@id">P28561331</replace> <replace sel="/MPD/Period[3]/@start">PT476022H11M</replace>

Relates to #155 and #174