Consider removing BulkWaarnemingenService

[veenstrajelmer]

The AanvragenBulkWaarnemingen endpoint test was commented out in #124 since it was not yet available in the New WaterWebservices (404 status). Consider removing it from ddlpy since it it probably not used a lot (only by waterinfo). Also the maximum number of measurements that can be retrieved is the same as for OphalenWaarnemingen API, so it does not make a lot of sense to have this. Furthermore, there already never was a function in ddlpy.py that called this endpoint

Todo:

• AanvragenBulkWaarnemingen is missing from new waterwebservices Rijkswaterstaat/WaterWebservices#15
• remove all AanvragenBulkWaarnemingen related code in endpoints.json and test_endpoints.py, or re-enable the test when the API is available
• update whatsnew >> no public functions changed, so not required

[TvLoon-RWS]

The AanvragenBulkWaarnemingen endpoint wil keep existing in the background for Waterinfo, but will not be publically documented as it is bound to change regularly to conform to the needs of Waterinfo.