Fix Ordering of Responses from Batch Get Methods in Reporting V2

[tristanvuong2021]

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[riemanli]

Reviewed 6 of 9 files at r1, 3 of 3 files at r2, all commit messages.
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src/main/proto/wfa/measurement/internal/reporting/error_code.proto line 55 at r2 (raw file):

  /** Metric with the provided IDs does not exist. */
  METRIC_NOT_FOUND = 10;
}

nit: new line at the end of the file.

[stevenwarejones]

Reviewed 5 of 9 files at r1, 3 of 3 files at r2, 1 of 1 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @Marco-Premier)