Make max read size configurable #912

Job	Run time
unit	4m 23s
unit	4m 23s
e2e (TestMultipleChainHorcrux)	5m 8s
e2e (TestMultipleChainHorcrux)	5m 8s
e2e (TestChainPureHorcrux)	5m 20s
e2e (TestChainPureHorcrux)	5m 20s
e2e (TestDownedSigners2of3)	7m 3s
e2e (TestDownedSigners2of3)	7m 3s
e2e (TestDownedSigners3of5)	7m 28s
e2e (TestDownedSigners3of5)	8m 20s
e2e (TestLeaderElection2of3)	5m 35s
e2e (TestLeaderElection2of3)	5m 35s
e2e (Test2Of3SignerThreeSentries)	4m 58s
e2e (Test2Of3SignerThreeSentries)	4m 58s
e2e (Test2Of3SignerThreeSentriesUniqueConnection)	4m 58s
e2e (Test2Of3SignerThreeSentriesUniqueConnection)	4m 58s
e2e (TestUpgradeValidatorToHorcrux)	5m 9s
e2e (TestUpgradeValidatorToHorcrux)	5m 9s
e2e (TestSingleSignerTwoSentries)	4m 58s
e2e (TestSingleSignerTwoSentries)	4m 58s
e2e (TestHorcruxProxyGRPC)	5m 3s
e2e (TestHorcruxProxyGRPC)	5m 3s
	2h 0m 58s

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