[dbapi] Stop shadowing exceptions in get_repository() (closes #2710515) Exceptions are already handled higher up in the stack so there's no reason to handle them here. Furthermore, non-ConnectionError exceptions would get hidden, making debugging harder.

Latest changes 
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* table of `all latest changes`_

Links below is providing useful RQL query example.

.. _all latest changes: view?rql=Any+M%2CX+WHERE+X+modification_date+M+ORDERBY+M+DESC+LIMIT+30