test/boost/mutation_reader_test: remove unused puppet_reader
test/boost/mutation_reader_test: remove unused puppet_reader

All users use puppet_reader_v2 now.

Signed-off-by: Botond Dénes <a584fa4d75a0a85d721f44fb6e06315a2853b0b6@scylladb.com>
Message-Id: <20220316135525.211753-1-a584fa4d75a0a85d721f44fb6e06315a2853b0b6@scylladb.com>

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