Raise the downloaded series limit to 10000

Requested by @MichelJuillard

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• As a user
• I want to download Excel files with more than 1000 series
• in order to work with data.

Acceptance criteria

• Excel and CSV files MUST be downloadable with up to 10000 series
• The current default value of 1000 series MUST be kept

Tasks

• analyse the impact of raising the limit to 10000 => test on some big dataset
• update dbnomics-web-api limits
• update dbnomics-website HTTP request default limit parameter