[Fleet] Remove deprecated ML job property from test fixtures (elastic…

…#207857)

## Summary

Replace `estimated_heap_memory_usage_bytes` property with `expected
model_size_bytes` per deprecation warning. I unzipped the fixture
archives, replaced the property, and rezipped them.

## To test

Add the following to your `serverArgs` block in
`x-pack/test/fleet_api_integration/config.base.ts`

```
{
  name: 'elasticsearch.debug',
  level: 'debug',
  appenders: ['default'],
},
```

Run the EPM FTR tests e.g.

```
FLEET_PACKAGE_REGISTRY_PORT=12345 yarn test:ftr:server --config x-pack/test/fleet_api_integration/config.epm.ts

# in another terminal session
FLEET_PACKAGE_REGISTRY_PORT=12345 yarn test:ftr:runner --config x-pack/test/fleet_api_integration/config.epm.ts --grep "Assets tagging"
```

Check that the deprecation notice does not appear in the
`elasticsearch.debug` logs in your console

```
x-pack/test/fleet_api_integration/apis/epm/bulk_get_assets.ts: Deprecated field estimated_heap_memory_usage_bytes used, expected model_size_bytes instead
```

(cherry picked from commit 4073aff)