fix(jsii-pacmak): emit correct @return tag for JavaDocs (#4095)

We are currently emitting `@returns`, but:

```
error: unknown tag: returns
* @returns a newly built instance of {@link software.amazon.awscdk.services.codedeploy.EcsDeploymentConfig}.
```

It should be `@return`.



---

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[Apache 2.0 license]: https://www.apache.org/licenses/LICENSE-2.0

packages/jsii-pacmak/lib/targets/java.ts

@@ -2226,7 +2226,7 @@ class JavaGenerator extends Generator {
     this.code.line();
     this.code.line('/**');
     this.code.line(
-      ` * @returns a newly built instance of {@link ${builtType}}.`,
+      ` * @return a newly built instance of {@link ${builtType}}.`,
     );
     this.code.line(' */');
     this.emitStabilityAnnotations(cls.initializer);