Fix etrago_id conflicts

[ClaraBuettner]

To avoid conflicts with using the same index for eTraGo tables, eMobilit currently has many dependencies. But the problem should be fixed differently (see https://github.com/openego/eGon-data/pull/927) By then, the dependencies for eMobility should be removed. These were added in this commit: https://github.com/openego/eGon-data/commit/a0d3db3ae6e28e9144b0b7a431b48ff91dedd603

Options to fix this problem

• reserve and store ids in seperate sequence
• write data into intermediate tables
• use combination of carrier and index as id