blockstore: only consume duplicate proofs from root_slot + 1 on startup #3365

Job	Run time
android (ubuntu-20.04, x86_64-linux-android)	2m 54s
ios (macos-12, aarch64-apple-ios)	4m 41s
android (ubuntu-20.04, aarch64-linux-android)	3m 2s
ios (macos-12, x86_64-apple-ios)	4m 59s
ios (macos-12, aarch64-apple-darwin)	4m 43s
android (ubuntu-20.04, i686-linux-android)	2m 58s
ios (macos-12, x86_64-apple-darwin)	4m 27s
android (ubuntu-20.04, armv7-linux-androideabi)	3m 9s
error_reporting	0s
	30m 53s

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