[BUG] S3 source csv codec parsing

Describe the bug
S3 source with csv codec is not paring the csv file accurately. It appends an additional space before the first key.

To Reproduce
Steps to reproduce the behavior:

1. create pipeline with S3 source and csv codec
2. ingest some csv data

Pipeline config:

log-pipeline:
  source:
    s3:
      notification_type: "sqs"
      compression: none
      codec:
        csv:
      sqs:
        queue_url: "https://sqs.us-east-1.amazonaws.com/<account-id>/<queue-name>"
      aws:
        region: "us-east-1"
        sts_role_arn: "arn:aws:iam::<account-id>:role/<role>"
      on_error: "retain_messages"

  processor:
    - date:
        from_time_received: true
        destination: "@timestamp"
   - delete_entries:
       with_keys: ["col1"]

  sink:
    - stdout:

Input:

col1,col2
a,101
b,102

Output:

{" col1":"a","col2":"101","s3":{"bucket":"bucket-name","key":"Book1.csv"},"@timestamp":"2023-04-10T14:48:53.411-05:00"}
{" col1":"b","col2":"102","s3":{"bucket":"bucket-name","key":"Book1.csv"},"@timestamp":"2023-04-10T14:48:53.580-05:00"}

Expected behavior

• There shouldn't be a space before col1 in above output and delete_entries should delete the key.

Start by reproducing the S3 source with the CSV codec using the pipeline configuration and input shown in the issue. Trace the S3 source and CSV codec handling to determine why the first key includes an extra space or character, then verify that the expected keys are parsed and delete_entries removes col1.