[Kafka proxy] Bug: messages larger than 6mb can't be read through ssl

[a-serebryanskiy]

Topic consumption through Kafka API with SSL enabled fails:

• on processing historic data (where small messages have been already compacted to large 8mb blobs)
• on processing one large message (>6Mb)

How to reproduce:

• set up YDB cluster with SSL enabled
• write to YDB large message (>6Mb)
• read from YDB through Kafka API with security.protocol=SASL_SSL
• you will see EOF exception and connection termination during fetch request