The regression test for bug 266907 randomly fails. After deleting the
.project file in the first workspace session of the test, an
asynchronously executed save operation non-deterministically restores
the .project file, which is assumed to be non-existing in the second
workspace session.

With this change, the JobManager is suspended in the according workspace
session to ensure that no asynchronous save operation restoring the
.project file is executed. This is valid and reasonable since no job
executions are required in the test and it prevents an auto-save job
from being executed.