Jingle: Fix UnboundLocalError for transports variable

transport=None is handled in JingleTransportSocks5()

Fixes #10545
2 jobs for master in 7 minutes and 4 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #22130
code-quality

00:05:22

3.0%
 
  Build
passed #22131
windows

00:01:42