Remove "gt.datafeed" from id_connector.

[hugograf]

Which part and what Version?
Version: 0.10.0
[ ] Internal structure (user should not notice)
[x] Improvement for the user

Problem
Currently, the data source references have a prefix of "gt.datafeed". This should be removed because application.properties is no longer used for API keys.

Solution
With the next database update these prefixes will be removed from the database and the program will be adjusted accordingly. The entities securitycurrency, security and globalparamers are affected.

It may be better to switch to numerical identification. This would allow "id_entity" of the table "mail_entity" to be used for displaying connector-specific errors in the messaging system.