`y-label` field does not set the title of the Y axis

There is a y_label field to customize the name of the Y Label on the chart, which if not set defaults to "Values". We should support this field in the FE.

There is data in this prometheus server if you have a production environment deployed: https://gitlab.35.185.40.222.nip.io So on a project that has a production environment, set that as your Prometheus URL after adding the below metrics to additional_metrics.yml and the data should show.

Here is my metrics file:

- group: AWS Elastic Load Balancer
  priority: 10
  metrics:
  - title: "Request Rate"
    y_label: "Requests/Min"
    required_metrics:
      - aws_elb_request_count_sum
    weight: 1
    queries:
    - query_range: 'aws_elb_request_count_sum{%{environment_filter}}'
      label: Requests per minute
      unit: requests
  - title: "Latency"
    y_label: "Average Latency"
    required_metrics:
     - aws_elb_latency_average
    weight: 1
    queries:
    - query_range: 'aws_elb_latency_average{%{environment_filter}}'
      unit: seconds
  - title: "Error Rate"
    y_label: "Percent HTTP Errors / minute"
    required_metrics:
     - aws_elb_request_count_sum
     - aws_elb_httpcode_backend_5_xx_sum
    weight: 1
    queries:
    - query_range: 'aws_elb_httpcode_backend_5_xx_sum{%{environment_filter}} / aws_elb_request_count_sum{%{environment_filter}}'