use buffer sizes only once in performance tests
use buffer sizes only once in performance tests

Remove duplicates from given buffer sizes in performance tests.
Additionally, sort buffer sizes for better grouping in logs and add a
colon before printing the measurements.

randombit/botan,randombit/botan,randombit/botan,Rohde-Schwarz-Cybersecurity/botan,webmaster128/botan,randombit/botan,Rohde-Schwarz-Cybersecurity/botan,Rohde-Schwarz-Cybersecurity/botan,Rohde-Schwarz-Cybersecurity/botan,webmaster128/botan,webmaster128/botan,Rohde-Schwarz-Cybersecurity/botan,webmaster128/botan,randombit/botan,Rohde-Schwarz-Cybersecurity/botan,webmaster128/botan