Description of changes:

Previously, we hackily called "shutdown" on the openssl connection to ensure that the session ticket was valid.

Now that we have actual shutdown utilities we can deal with this more cleanly by just calling ".shutdown()" when the ticket is generated.

Remember:

• Any change to the library source code should at least include unit tests.
• Any change to the core stuffer or blob methods should include CBMC proofs.
• Any change to the CI or tests should:
  1. prove that the test succeeds for good input
  2. prove that the test fails for bad input (eg, a test for memory leaks fails when a memory leak is committed)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.