minor: remove unnecessary @SuppressWarning annotations

...ystemsx/cisd/openbis/generic/shared/dto/ExperimentPE.java

.../application/experiment/ExperimentAttachmentsSection.java

...lient/application/experiment/GenericExperimentViewer.java

...nt/web/client/application/sample/GenericSampleViewer.java

...tion/ui/property_type/FillPropertyTypeAssignmentForm.java

...pplication/experiment/FillExperimentRegistrationForm.java

...client/application/sample/FillSampleRegistrationForm.java

...t/web/server/ExperimentAttachmentDownloadServletTest.java