[0.16] Fix horreum-client javadoc generation

[rh-appservices-perf]

Backport: #2179

Fixes Issue

Fixes the horreum-client generation, in particular:

Error:  /home/runner/work/Horreum/Horreum/horreum-client/src/main/java/io/hyperfoil/tools/auth/HorreumApiKeyAuthentication.java:10: error: reference not found
Error:      /** sync with {@link io.hyperfoil.tools.horreum.server.ApiKeyAuthenticationMechanism} */
Error:                           ^

Changes proposed

Remove the link in the javadoc comment

Check List (Check all the applicable boxes)

• My code follows the code style of this project.
• My change requires changes to the documentation.
• I have updated the documentation accordingly.
• All new and existing tests passed.