fix(api): Fix getPrimaryKeyString for non-string CPK with no sort keys (#2502)

Author: tylerjroach

core/src/main/java/com/amplifyframework/core/model/Model.java

@@ -69,12 +69,8 @@ default String getPrimaryKeyString() {
         try {
             if (resolveIdentifier() instanceof ModelIdentifier) {
                 return ((ModelIdentifier<?>) resolveIdentifier()).getIdentifier();
-            } else if (resolveIdentifier() instanceof String) {
-                return (String) resolveIdentifier();
             } else {
-                return ModelIdentifier.Helper.escapeAndEncapsulateString(
-                        resolveIdentifier().toString()
-                );
+                return resolveIdentifier().toString();
             }
         } catch (Exception exception) {
             throw (new IllegalStateException("Invalid Primary Key", exception));

core/src/test/java/com/amplifyframework/core/model/ModelIdentifierTest.kt

@@ -44,7 +44,7 @@ class ModelIdentifierTest {
     @Test
     fun cpk_non_string_without_model_identifier_with_no_sort_key() {
         val expectedKey = 123
-        val expectedKeyString = "\"123\""
+        val expectedKeyString = "123"
 
         val identifier = IntModelWithoutIdentifier.builder().customId(expectedKey).build().primaryKeyString