Remove execute_and_save function

[tkv29]

Description:
This tasks inlcudes the removal of the execute_and_save function. With the removal we only have one execute function, so we dont need the if the statements to run thee modules which have the execute_and_save function. For that we need to change the primary key schema. Currently the execute_and_save functions returns an int, so later when we are saving the results to db we can make the connection between the results. We can avoid that by using predefined primary keys which are following a specifc schema, so we dont need to return an int and can pass a dataframe.

Acceptance Criteria

• defining pre-defined primary key schema where necessary
• changing current int primary keys to predefined schema
• replace execute_and_save with execute method