fix(reduce transform): enable quoting for invalid fields

[pront]

Summary

#21323 added unquoted iterators but it also made the other iterators return unquoted fields.

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

How did you test this PR?

transforms:
  transform0:
    type: reduce
    inputs:
      - my_input
    group_by:
      - id
    expire_after_ms: 2000
    max_events: 500
    merge_strategies:
      foo: array
tests:
  - name: map_transform0.space
    inputs:
      - type: vrl
        insert_at: transform0
        source: |
          . = {
            "a b": 1
          }
      - type: vrl
        insert_at: transform0
        source: |
          . = {
            "a b": 1
          }
    outputs:
      - extract_from: transform0
        conditions:
          - type: vrl
            source: |
              assert_eq!(., {"a b": 2})

Also added a unit test to cover this.

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the "no-changelog" label to this PR.

Checklist

• Please read our Vector contributor resources.
• If this PR introduces changes Vector dependencies (modifies Cargo.lock), please
  run dd-rust-license-tool write to regenerate the license inventory and commit the changes (if any). More details here.

References

• Closes: Reduce transform cannot handle keys with spaces #21983

[datadog-vectordotdev]

Datadog Report

Branch report: pront/fix-reduce-wrong-config
Commit report: dab517c
Test service: vector

✅ 0 Failed, 7 Passed, 0 Skipped, 25.45s Total Time