(TK-37) Cleanup based on PR comments

Cleanup code based on comments received on the PR. Use default
variables instead of hardcoded numbers for the requestBufferSize
and requestHeaderSize. Change the name of the key to configure
the request header size. Cleanup config tests by adding the
default request header size within expected-http-config?
and expected-https-config?. Ensure Jetty does not truncate
large header.
(TK-37) Update docs to reflect new option

Update docs to reflect the new option to configure the maximum
request header size.