[Instabot] Relocate CmdlineBotBuilder cookie jar creation
[Instabot] Relocate CmdlineBotBuilder cookie jar creation

Reusing the same instance for all bots should avoid conflicts when
multiple bots are created from the same builder (although thread
safety remains an issue...).

CylonicRaider/Instant,CylonicRaider/Instant,CylonicRaider/Instant,CylonicRaider/Instant,CylonicRaider/Instant