Fix arm architecture translation issue (opensearch-project#809)

Found when attempting to build on an `arm64` machine when I recieved an error message below.  Root cause is that string equality in java cannot be done with the `==` sign.

```
unknown architecture [arm64] for jdk [provisioned_runtime], must be one of [aarch64, x64]
```

Signed-off-by: Peter Nied <[email protected]>

buildSrc/src/main/java/org/opensearch/gradle/Jdk.java

@@ -234,7 +234,7 @@ private String translateJdkArchitecture(String architecture) {
         /*
          * Jdk uses aarch64 from ARM. Translating from arm64 to aarch64 which Jdk understands.
          */
-        return architecture == "arm64" ? "aarch64" : architecture;
+        return "arm64".equals(architecture) ? "aarch64" : architecture;
     }
 
 }