BIS-1335: Removed grouping of sections names. Fixed failing tests.

...ric/server/asapi/v3/executor/exporter/ExportExecutor.java

...bis/systemtest/asapi/v3/test_files/export/TEST-SPACE.html

...mtest/asapi/v3/test_files/export/export-data-set-html.zip

...t_files/export/export-experiment-filtered-fields-html.zip

...est/asapi/v3/test_files/export/export-experiment-html.zip

...test_files/export/export-project-filtered-fields-html.zip

...emtest/asapi/v3/test_files/export/export-project-html.zip

...files/export/export-sample-all-compatible-with-import.zip

...stemtest/asapi/v3/test_files/export/export-sample-all.zip

.../test_files/export/export-sample-filtered-fields-html.zip

...temtest/asapi/v3/test_files/export/export-sample-html.zip

...pi/v3/test_files/export/export-sample-plain-text-html.zip

...api/v3/test_files/export/export-sample-rich-text-html.zip

.../asapi/v3/test_files/export/export-sample-shared-html.zip

...pi/v3/test_files/export/export-sample-with-image-html.zip

...test_files/export/export-sample-with-spreadsheet-html.zip

...3/test_files/export/export-space-filtered-fields-html.zip

...stemtest/asapi/v3/test_files/export/export-space-html.zip