Increase test coverage for Recommended Test 6.2.31 (CSAF 2.1)

[bendo-eXX]

According to the specification for Recommended Test 6.2.31 (CSAF 2.1), there is a relevant path for full_product_name. Currently, there is no test case covering this path, resulting in a gap in test coverage.

Proposal:
oasis_csaf_tc-csaf_2_1-2024-6-2-31-02.json
oasis_csaf_tc-csaf_2_1-2024-6-2-31-14.json

Please add a corresponding test to ensure full compliance with the specification and increase the code coverage.

[bendo-eXX]

This has been announced on the CSAF TC comment mailing list: https://groups.oasis-open.org/discussion/increase-test-coverage-for-recommended-test-6231