Fix app compat issue by not enabling TLS 1.3 by default.

An app was opening a connection to a literal IPv6 address,
but did not specify the expected server name (via
SSLParameters.setServerNames()). This caused SNI (server
name indication) to be disabled, which the server required.

This CL was created by running:

  git revert f32607b9
  srcgen/generate_android_src.sh

The reverted commit was "Enable TLS 1.3 by default (#595)".

This reverts commit f32607b9.

Fixes: 121382720
Test: Manually checked that applying the corresponding change
      on the internal master branch fixes the symptoms of the bug.

Change-Id: Ib0bcf3fa31e2a4ba42218fc10396387018254294