removing branch from documentAttributes in Container.snapshotBase

[chensixx]

part of removing container.id #2903
this also involves updating snapshot content so having a separate pr

[msfluid-bot]

⯆ @fluid-example/bundle-size-tests: -15 Bytes

Metric Name	Baseline Size	Compare Size	Size Diff
aqueduct.js	379.61 KB	379.61 KB	■ No change
containerRuntime.js	178.85 KB	178.85 KB	■ No change
loader.js	160.46 KB	160.45 KB	⯆ -15 Bytes
map.js	50.98 KB	50.98 KB	■ No change
matrix.js	145.5 KB	145.5 KB	■ No change
odspDriver.js	192.72 KB	192.72 KB	■ No change
odspPrefetchSnapshot.js	45.08 KB	45.08 KB	■ No change
sharedString.js	166.54 KB	166.54 KB	■ No change
Total Size	1.32 MB	1.32 MB	⯆ -15 Bytes

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Baseline commit: 7665d40

Generated by 🚫 dangerJS against d65038a