Updating Netherlands contract renewal policy

Why is this change being made?

After hearing feedback from Team Members and Recruiting we are moving forward with 1 fixed term 12 month contract and then indefinite, rather than doing two consecutive 12 month fixed term contracts

Author Checklist

• [x ] Provided a concise title for this Merge Request (MR)
• [ x] Added a description to this MR explaining the reasons for the proposed change, per say why, not just what
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• [x ] Assign reviewers for this MR to the correct Directly Responsible Individual/s (DRI)
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• If the changes affect team members, or warrant an announcement in another way, please consider posting an update in #whats-happening-at-gitlab linking to this MR
  • If this is a change that directly impacts the majority of global team members, it should be a candidate for #company-fyi. Please work with internal communications and check the handbook for examples.

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