Is your feature request related to a problem? Please describe.
I'd like to use the metric property for better filtering of the eval results. My current config looks similar to this one:
promptfooconfig.yaml:

providers:
  - file://my_provider.yaml
defaultTest:
  assert:
    - type: llm-rubric
      threshold: 0.1
      metric: '{{metric}}'
prompts:
  - '{{userPrompt}}'
tests:
  - file://my_tests.yaml

my_tests.yaml (contains at least a few hundred prompts):

- vars:
  userPrompt: "Some prompt"
  metric: "metric1"
- vars:
  userPrompt: "Some other prompt"
  metric: "other"

Describe the solution you'd like
I'd expect to see the metrics on the UI where I could filter for them, however what I see is just {{metric}}: 50.00% (1.00/2.00).
What I'd like to see is: metric1: 50.00% (1.00/2.00) | other: 50.00% (1.00/2.00)

Describe alternatives you've considered
I don't want to expand the assert for each prompt in the my_tests.yaml, because I like how it's compact in the defaultTests.assert

Additional context
Promptfoo version: 0.116.7