[test] avoid using rnorm in checks. For some reason this is failing i…

[JanMarvin]

…n a current CRAN release, but we should be able to avoid this.

From here

══ Failed tests ════════════════════════════════════════════════════════════════
  ── Failure ('test-read_from_created_wb.R:173:3'): reading with pre defined types works ──
  `got` (`actual`) not equal to `dat` (`expected`).
  
    `actual[[4]]`: 1729991700 1729991699 1729991698 1729991697 1729991696
  `expected[[4]]`: 1729988100 1729988099 1729988098 1729988097 1729988096
  
  [ FAIL 1 | WARN 0 | SKIP 69 | PASS 1624 ]

[JanMarvin]

Error went away and is not reproduceable so far. Therefore closing