Transfer network bytes to smaller buffer

[Tim-Brooks]

Currently we read in 64KB blocks from the network. When TLS is not
enabled, these bytes are normally passed all the way to the application
layer (some exceptions: compression). For the HTTP layer this means that
these bytes can live throughout the entire lifecycle of an indexing
request.

The problem is that if the reads from the socket are small, this means
that 64KB buffers can be consumed by 1KB or smaller reads. If the socket
buffer or TCP buffer sizes are small, the leads to massive memory
waste. It has been identified as a major source of OOMs on coordinating
nodes as Elasticsearch easily exhausts the heap for these network bytes.

This commit resolves the problem by placing a handler after the TLS
handler to copy these bytes to a more appropriate buffer size as
necessary. This comes after TLS, because TLS is a framing layer which
often resolves this problem for us (the 64KB buffer will be decoded
into a more appropriate buffer size). However, this extra handler will
solve it for the non-TLS pipelines.

[elasticmachine]

Pinging @elastic/es-distributed (:Distributed/Network)

[Tim-Brooks]

@elasticmachine run elasticsearch-ci/packaging-sample-windows