sql/importer: TestImportDistributedMergeStoragePrefixTracking failed

sql/importer.TestImportDistributedMergeStoragePrefixTracking [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Ci_TestsAwsLinuxArm64_UnitTests/21515565?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Ci_TestsAwsLinuxArm64_UnitTests/21515565?buildTab=artifacts#/) on master @ [547a6f07664c48289732d8000c580466b8c2ec6d](https://github.com/cockroachdb/cockroach/commits/547a6f07664c48289732d8000c580466b8c2ec6d):

```
=== RUN TestImportDistributedMergeStoragePrefixTracking
test_log_scope.go:172: test logs captured to: /artifacts/tmp/_tmp/01d4c2296171c02c8682f9521e301182/logTestImportDistributedMergeStoragePrefixTracking3961566968
test_log_scope.go:82: use -show-logs to present logs inline
test_server_shim.go:168: automatically injected an external process virtual cluster under test; see comment at top of test_server_shim.go for details.
test_server_shim.go:637: DRPC is enabled (via testserver factory defaults)
import_stmt_test.go:6430:
Error Trace: pkg/sql/importer/import_stmt_test.go:6430
Error: Should NOT be empty, but was []
Test: TestImportDistributedMergeStoragePrefixTracking
panic.go:694: -- test log scope end --
test logs left over in: /artifacts/tmp/_tmp/01d4c2296171c02c8682f9521e301182/logTestImportDistributedMergeStoragePrefixTracking3961566968
--- FAIL: TestImportDistributedMergeStoragePrefixTracking (3.68s)
```
Help

See also: [How To Investigate a Go Test Failure \(internal\)](https://cockroachlabs.atlassian.net/l/c/HgfXfJgM)

/cc @cockroachlabs/sql-foundations

[Improve this report!](https://github.com/cockroachdb/cockroach/tree/master/pkg/cmd/bazci/githubpost/issues)

Jira issue: CRDB-68392

Start by reproducing TestImportDistributedMergeStoragePrefixTracking and inspect the failing assertion at pkg/sql/importer/import_stmt_test.go:6430. Review the TeamCity log and artifacts for the run at commit 547a6f07664c48289732d8000c580466b8c2ec6d. Done means the test passes with non-empty prefix-tracking results.

Written by the indexing model from the issue text.