flake: scaletest/createworkspaces: Test_Runner/CleanupPendingBuild: condition was never satisfied

Seen here: https://github.com/coder/coder/actions/runs/12997421114/job/36248389337?pr=16303#step:8:872

```
    run_test.go:301: 
        	Error Trace:	/home/runner/work/coder/coder/scaletest/createworkspaces/run_test.go:301
        	Error:      	Condition never satisfied
        	Test:       	Test_Runner/CleanupPendingBuild

```