aws-for-fluent-bit: allow extraParsers to override default parsers

[0x2b3bfa0]

Issue

When a parser defined in extraParsers has the same name as one of the default parsers, it will be ignored with the following message:

[2025/02/08 05:00:54] [error] [parser] parser named 'json' already exists, skip.

Description of changes

After changing the order of the Parsers_File directives, extraParsers will take precedence over the default parsers in cases where there is a naming collisions.

Checklist

• Added/modified documentation as required (such as the README.md for modified charts)
• Incremented the chart version in Chart.yaml for the modified chart(s)
• Manually tested. Describe what testing was done in the testing section below
• Make sure the title of the PR is a good description that can go into the release notes

Testing

Create a parser named e.g. json with a time format other than the default one, and put it into values.yaml

service:
  extraParsers: |
    [PARSER]
      Name        json
      Format      json
      Time_Key    time
      Time_Format %Y-%m-%dT%H:%M:%S.%L
      Time_Keep   On

Run fluent-bit and check that it can parse log lines with the specified time format.

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