tests: use tenant_create() helper in test_bulk_insert

[jcsp]

Problem

Since #5449 we enable generations in tests by default. Running benchmarks was missed while merging that PR, and there was one that needed updating.

Summary of changes

Make test_bulk_insert use the proper generation-aware helper for tenant creation.

Checklist before requesting a review

• I have performed a self-review of my code.
• If it is a core feature, I have added thorough tests.
• Do we need to implement analytics? if so did you add the relevant metrics to the dashboard?
• If this PR requires public announcement, mark it with /release-notes label and add several sentences in this section.

Checklist before merging

• Do not forget to reformat commit message to not include the above checklist

[bayandin]

LGTM if tests work 👍

[github-actions]

2528 tests run: 2426 passed, 0 failed, 102 skipped (full report)

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Flaky tests (5)

Postgres 16

• test_ondemand_download_timetravel[mock_s3]: debug
• test_pitr_gc: debug

Postgres 15

• test_statvfs_pressure_min_avail_bytes: debug
• test_gc_cutoff: debug

Postgres 14

• test_statvfs_pressure_usage: debug

Code coverage (full report)

• functions: 54.8% (9380 of 17112 functions)
• lines: 82.3% (54247 of 65947 lines)

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_{The comment gets automatically updated with the latest test results
e211548 at 2023-12-07T14:46:34.506Z :recycle:}