chore: remove tck module

The TCK server is now generated by the a2a-tck codegen tool,
making this hand-written module obsolete.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jmesnil

pom.xml

@@ -570,7 +570,6 @@
         <module>server-common</module>
         <module>spec</module>
         <module>spec-grpc</module>
-        <module>tck</module>
         <module>test-utils-docker</module>
         <module>tests/server-common</module>
         <module>transport/jsonrpc</module>