Updated gitleaksignore file for false positive on User-Agent value

Author: jhyde15

.gitleaksignore

@@ -4,3 +4,5 @@ cd9c0efec38c5d63053dd865e5d4e207c0760d91:docs/guides/Perform_static_analysis.md:
 edcce0d54ce30fe8797a5f27ea13eb48f597462b:performance-tests/reporting-journey.jmx:ipv4:37
 954013eeb7f6dce8cb837f2b825c910ac6b9bafc:performance-tests/give-or-refuse-consent-journey.jmx:ipv4:75
 236d121ec520247f72d13b1d2119c0fde50cc85d:performance-tests/nurse-journey.jmx:ipv4:36
+2254b42e5784abecc1cf5c9016107c105577b8b8:performance-tests/upload-cohort-data.jmx:ipv4:35
+2254b42e5784abecc1cf5c9016107c105577b8b8:performance-tests/upload-cohort-data.jmx:ipv4:483