Remove SRT-specific rendition properties

[bquinn]

Original issue: Do we still need SRT properties in the next version of ninjs?

See conversations with DPP LPX team - we want to only include the bare minimum that we need for now.

[bquinn]

We discussed this again with the DPP LPX steering group on a call yesterday. We agreed that we only need the bare minimum for DPP LPX, as per [David Thompson's spreadsheet]:(https://docs.google.com/spreadsheets/d/1iWtm4LR_ZyVJohKUcXhQ5YOgnFqOh_syopAhHaSJtx8/edit?gid=1717449119#gid=1717449119).

renditions			Object	An array of objects, each of which is a rendition of the event.	“Renditions” : []
	name		String	Live event rendition name.	"200Kbps-4Mbps Video:1080p29.97 h.264"
	videoCodec		String	Live event video codec	"h.264"
	frameRate		String	Live event frame rate	"29.97"
	scanType		String	Live event scan type	"progressive"
	aspectRatio		String	Live event aspect ratio	"16:9"
	width		Int	Live event frame width	"1920"
	height		Int	Live event frame height	"1080"
	bitrate		String	Live event overall bitrate (kbps)	"4000"
	transportProtocol		String	Live event Transport Protocol	"SRT Caller"
	url		String	Live event URL

[bquinn]

Will be fixed by #195 when it's merged.