datastore adds UTC mark to AWSTime values even when they don't have it - dev preview

### Before opening, please confirm:

- [X] I have [searched for duplicate or closed issues](https://github.com/aws-amplify/amplify-android/issues?q=is%3Aissue+) and [discussions](https://github.com/aws-amplify/amplify-android/discussions).

### Language and Async Model

Kotlin

### Amplify Categories

DataStore

### Gradle script dependencies

```groovy
// Put output below this line
dependencies {
api amplifyFlutter

implementation "com.amplifyframework:aws-datastore:1.36.5-dev-preview.0"
implementation "com.amplifyframework:aws-api-appsync:1.36.5-dev-preview.0"

testImplementation 'junit:junit:4.13.2'
testImplementation 'org.mockito:mockito-core:4.0.0'
testImplementation 'org.mockito:mockito-inline:3.11.2'
testImplementation 'androidx.test:core:1.4.0'
// Tests must be updated if bumped
//noinspection GradleDependency
testImplementation 'org.robolectric:robolectric:4.3.1'
testImplementation 'com.fasterxml.jackson.core:jackson-core:2.12.4'
testImplementation 'com.fasterxml.jackson.core:jackson-annotations:2.12.4'
testImplementation 'com.fasterxml.jackson.core:jackson-databind:2.12.4'
}

```

### Environment information

```
# Put output below this line

------------------------------------------------------------
Gradle 7.2
------------------------------------------------------------

Build time: 2021-08-17 09:59:03 UTC
Revision: a773786b58bb28710e3dc96c4d1a7063628952ad

Kotlin: 1.5.21
Groovy: 3.0.8
Ant: Apache Ant(TM) version 1.10.9 compiled on September 27 2020
JVM: 11.0.14.1 (Homebrew 11.0.14.1+0)
OS: Mac OS X 12.6 x86_64

```

### Please include any relevant guides or documentation you're referencing

_No response_

### Describe the bug

Found as a bug in flutter dev-preview https://github.com/aws-amplify/amplify-flutter/issues/2214 which uses amplify-android dev preview.

If I have a model with type of AWSTime and I save a time that does not include timezone (which is optional), the version of the model that I query from the datastore will always include "Z" to indicate UTC.

Expected: AWSTime values respect inclusion/omitting timezone as saved

### Reproduction steps (if applicable)

Save a model with a value of type `AWSTime` with no timezone offset set. Then, query that from the datastore and the model will have a timezone offset added "Z" which is optional, but should reflect how user saved it. I'm not sure if saved that way or happens during query.

### Code Snippet

```java
// Put your code below this line.

```

### Log output

```
// Put your logs below this line

```

### amplifyconfiguration.json

_No response_

### GraphQL Schema

```graphql
// Put your schema below this line

```

### Additional information and screenshots

_No response_