Changed methodology for benchmarks

• Usage of pytest-benchmarks is dropped since it call tests sequentially which very long time to complete, instead original tavern tests are used
• Time measuring is done via durations switch to pytest and tavern
• During benchmarking validate_response.py is disabled using nevly introduced env variable
• Each run creates xml junit file with time data
• After all runs data from files are combined and report file is generated
• Tests above threshold are marked with red