[PLT-1357] Vb/fixtures for feature schemas plt 1342

[vbrodsky]

Description

This PR is a follow up in addition to https://labelbox.atlassian.net/browse/PLT-1342 to allow better handling of feature schemas. I have fixed feature schema leaks and flaky tests that were causing original performance issues on stage.

Note we still have many feature schema leaks to fix. I have created https://labelbox.atlassian.net/browse/PLT-1379 to address it post-alignerr

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Document change (fix typo or modifying any markdown files, code comments or anything in the examples folder only)

All Submissions

• Have you followed the guidelines in our Contributing document?
• Have you provided a description?
• Are your changes properly formatted?

New Feature Submissions

• Does your submission pass tests?
• Have you added thorough tests for your new feature?
• Have you commented your code, particularly in hard-to-understand areas?
• Have you added a Docstring?

Changes to Core Features

• Have you written new tests for your core changes, as applicable?
• Have you successfully run tests with your changes locally?
• Have you updated any code comments, as applicable?

[vbrodsky]

These are actual changes. Above is just lint automated changes