Add new check to exclude specific prefixes from generating events

[richardhallett]

This is to be used in cases where we want to handle event generation at a later point.

Purpose

Allow specific exclusion for certain prefixes

This is to help especially when ingesting larget amounts of new DOIs

Approach

Check env var for prefix trying to index

Open Questions and Pre-Merge TODOs

Learning

Types of changes

• Bug fix (non-breaking change which fixes an issue)

• New feature (non-breaking change which adds functionality)

• Breaking change (fix or feature that would cause existing functionality to change)

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