Update BulkImports::Pipeline::NDJSON_EXPORT_TIMEOUT to be 90 minutes

What does this MR do and why?

This MR bumps NDJSON_EXPORT_TIMEOUT from 30 to 90 minutes. This timeout value is used by BulkImports::PipelineWorker when waiting for relation export to be completed on source instance of GitLab, in order to download it and import data on destination instance.

For big projects with a lot of data, for example 50k CI pipelines, it takes more than 30 minutes to export this relation, which makes PipelineWorker to fail due to export timeout as seen in #365702 (closed) & #360510 (closed)

This MR bumps the timeout value in order to allow larger project relations to have time to export the data and then download it during the migration.

We already have a test for this timeout setting https://gitlab.com/gitlab-org/gitlab/blob/geogekoltsov%2Fadd-import-export-mr-approvals/spec/workers/bulk_imports/pipeline_worker_spec.rb#L339-362

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