release-24.3: logictest: skip distsql_numtables under race

[yuzefovich]

Backport 1/1 commits from #160397 on behalf of @yuzefovich.

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We've seen a timeout in this test twice under race with no clear signs of things going wrong, other than the cluster being overloaded - it uses 5node config, so let's just skip it under race.

Fixes: #160391.
Release note: None

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Release justification: test-only change.

[blathers-crl]

Thanks for opening a backport.

Before merging, please confirm that it falls into one of the following categories (select one):

• Non-production code changes. Includes test-only changes, build system changes, etc.
• Fixes for serious issues. Defined in the policy as correctness, stability, or security issues, data corruption/loss, significant performance regressions, breaking working and widely used functionality, or an inability to detect and debug production issues.
• Other approved changes. These changes must be gated behind a disabled-by-default feature flag unless there is a strong justification not to.

Add a brief release justification to the PR description explaining your selection.

Also, confirm that the change does not break backward compatibility and complies with all aspects of the backport policy.

All backports must be reviewed by the TL and EM for the owning area.

[blathers-crl]

✅ PR #160411 is compliant with backport policy

Confidence: high
Backward compatible: true
Explanation: The pull request concerns changes to a file specifically listed under the test-only directories pattern (pkg/sql/logictest/testdata/), indicating that the changes affect non-production code. According to the CockroachDB Backport Policy, modifications to non-production, test-only files are exempt from the requirement to justify critical bugs or feature flag gating. The PR clearly denotes these changes as test-only modifications in the PR title and body, further emphasizing their compliance. The file in question, 'distsql_numtables', is part of the logic tests, which serve to verify correctness in a non-production environment rather than influence the production behavior of the database system.

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[cockroach-teamcity]

This change is