Fix traffic analysis for nodes attached to multiple nodes

[Carsopre]

In traffic_analysis_base.py we created the function _get_accumulated_traffic_from_node_list to handle a list of origins nodes which were contained within one node.
This is due to a fault when reading the graph, apparently the "centroid" used to find the closest origin gets attached to two (or many) different nodes, ideally we want to only attach to the closest one to the "centroid".

What needs to be done

• Make sure the traffic analysis does not calculate traffic for the described situation, just pick one of the nodes.
• Ensure the reading of the graph does not contain multiple nodes within one origin.

[Carsopre]

What was failing:
We were making a GeoDataFrame in analysis_indirect.find_route_ods with a list of nodes where more than one origin node was present within a lon / lat position, this will condition the rest of the ra2ce code using such dataframe.

What has been done:
When generating a list of tuples with origin - destination we expand the list so that no origin contains a list of names. So for such an entry [O1, O2, O3] - [D1] we create now 3 entries [O1 - D1], [O2-D1], [O3-D1].
This, however, does not prevent from duplicates in the GeoDataFrame. For such, just before returning the final structure for analysis_indirect.find_route_ods we will remove all duplicates where the o_node, d_node, destination, length and geometry are the same, taking the very first entry as prevalent.