fix kafka client_id. remove thread idxnum

[raistlinzx]

fix Fetch Exception caused by wrong client_id in ConsumerConfig

[elasticcla]

Hi @raistlinzx, we have found your signature in our records, but it seems like you have signed with a different e-mail than the one used in yout Git commit. Can you please add both of these e-mails into your Github profile (they can be hidden), so we can match your e-mails to your Github profile?

[elasticcla]

Hi @raistlinzx, we have found your signature in our records, but it seems like you have signed with a different e-mail than the one used in yout Git commit. Can you please add both of these e-mails into your Github profile (they can be hidden), so we can match your e-mails to your Github profile?

[raistlinzx]

#291 fixed

[w32-blaster]

The index in the client_id was introduced to support multiple threads (make the client_id across threads unique)