Fix duplicated row in metadata form and clean some MEPRAM initial config

[albatalavera]

Summary

This PR cleans up the MEPRAM initial configuration and fixes Excel template generation issues.

What changed

• Removed upload_to_gisaid from initial_config-MEPRAM.yaml as MEPRAM no longer expects GISAID upload configuration in the initial config
• Added read_lab_metadata_heading_default-MEPRAM.json with the default MEPRAM lab metadata headings
• Fixed DATA_VALIDATION formatting issues:
  • corrected header row count
  • removed duplicated first row

PR Checklist

• This comment contains a description of changes (with reason).
• Make sure your code lints (black and flake8).
• CHANGELOG.md is updated.
• README.md is updated (including new tool citations and authors/contributors).

[Shettland]

LGTM