test: remove blinding from self_talk_sesion_id test

[jmayclin]

This test is currently the second slowest test because it trigger blinding twice. The commit set's blinding to self serve so the test takes 4 seconds to execute instead of 40.

Testing:

I added a print statement to s2n_connection_kill sleep logic, and confirmed that there were no print statements in all of our unit tests after I added these connection settings.

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

[lrstewart]

This probably isn't the only test that still has this error. I've had to make this same change in other unit tests before :(

[jmayclin]

This probably isn't the only test that still has this error.

I think my little "printf if blinding sleep" test should have caught the low hanging ones, but if we're doing weird things with stdout there's definitely a chance that I missed some.