default `isLegacyGetEnabled` to false for `Data` and `Cache` api

Related to #531 , this flag is currently defaulted to `true`. We eventually will need to update this flag to default to `false`, in prep for eventually removing the flag.

> This should be a major release of hyper core

```
As a hyper developer
I would like hyper data service and hyper cache service "get" apis to return a hyper response shape, default
So that consumers can start to receive the hyper response shape that will be used, going forward
```

## Scenarios

Default to hyper response shape
```
GIVEN I am a developer
AND I am calling the Data Service "get document" or Cache Service "get value" api
WHEN I do NOT provide the `isLegacyGetEnabled` flag, ie. set `X-HYPER-LEGACY-GET` header
THEN I will receive the hyper response shape
```

Opt-in to legacy shape
```
GIVEN I am a developer
AND I am calling the Data Service "get document" or Cache Service "get value" api
WHEN I DO provide the `isLegacyGetEnabled` flag, ie. set `X-HYPER-LEGACY-GET` header
THEN I will receive the legacy shape (the document or value directly)
```