Fix checksum calculation bug when the payload is a CompositeByteBuf with readerIndex > 0 #1331

Job	Run time
PR Validation	7m 40s
Backward compatibility tests	3m 42s
Integration Tests	6m 50s
Bookie Tests	20m 52s
Client Tests	34m 23s
Replication Tests	24m 16s
Build with windows on JDK 11	8m 49s
Build with macos on JDK 11	6m 28s
Remaining Tests	19m 50s
Compatibility Check Java8	19m 28s
TLS Tests	13m 0s
Compatibility Check Java11	21m 21s
StreamStorage Tests	18m 33s
Compatibility Check Java17	19m 19s
OWASP Dependency Check	0s
Shell tests	21s
	3h 44m 52s

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