build(wasm-privacy-coin): remove unused jackson-databind test dependency

jackson-databind was added for JSON parsing in retention-flag tests, but
those tests were refactored to use Rust-level unit tests instead. The
dependency is no longer referenced anywhere in the test sources.

Ticket: CSHLD-785

Author: Ranjna-G

packages/wasm-privacy-coin/pom.xml

@@ -41,12 +41,6 @@
       <version>5.10.3</version>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>com.fasterxml.jackson.core</groupId>
-      <artifactId>jackson-databind</artifactId>
-      <version>2.17.0</version>
-      <scope>test</scope>
-    </dependency>
   </dependencies>
 
   <distributionManagement>