fix(PU): Rollback transaction when failing to import a file in setUpBeforeClass() (refs #4765)

A failed test with an error during the import of a ODS file in
setUpBeforeClass() could leave families and documents in the database.

A rollbackTransaction() is now performed before throwing the exception in
setUpBeforeClass() to cleanup the PU's elements.
Merge pull request #1310 from eguaj/3.2-A4765

fix(PU): Rollback transaction when failing to import a file in setUpBeforeClass() (closes #4765)