TLS backend SecureTransport: properly clear SSLContextRef
Simply calling SSLClose on context is not enough. Properly clear the context by calling 'reset' member-function.
Pick-to: 6.5 6.4 6.2 5.15 Change-Id: Ic6a32f6e4193bb19809d1cce184651b78d6273a7 Reviewed-by: Qt CI Bot qt_ci_bot@qt-project.org Reviewed-by: Mårten Nordheim marten.nordheim@qt.io (cherry picked from commit 6128a92e)