Remove fuzzy matching from VSD label filter

What does this MR do and why?

Updates the label filter query to use an exact match for the label names. Previously fuzzy matching was used, which would result multiple labels applied not the exact label specified in the config.

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Screenshots or screen recordings

Before - fuzzy search	After - exact search

How to set up and validate locally

1. Create 2 new labels in a group. Give the labels similar names: test label, test label advanced
2. Follow the docs to set up a custom VSD
3. Edit the YAML config for the dora_chart panel and add the test label as a filter. For example:

  - visualization: dora_chart
    queryOverrides:
      namespace: flightjs
      filters:
        labels:
          - test label

4. View the Value streams dashboard. Only the label with the exact title should be applied (exact search)
5. Switch to the master/main branch, return to the VSD and both labels should be returned (fuzzy search)

Related to #465548 (closed)