dtrace: backport two byte string fix

This is a partial backport of 5921158

Re #6309
Closes #6319
tls: fix premature connection termination

Destroying the TLS session implies destroying the underlying socket but
before this commit, that was done with net.Socket#destroy() rather than
net.Socket#destroySoon().  The former closes the connection right away,
even when there is still data to write.  In other words, sometimes the
final TLS record got truncated.

Fixes #6107.