tests: conformance test fixes

[feywind]

Description

This will fix as many conformance test failures as possible. It's a work in progress that will be open for a bit.

Checklist

• Make sure to open an issue as a bug/issue before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
• Ensure the tests and linter pass
• Code coverage does not decrease
• Appropriate docs were updated
• Appropriate comments were added, particularly in complex areas or places that require background
• No new warnings or issues will be generated from this change

Fixes #issue_number_goes_here 🦕

[generated-files-bot]

Warning: This pull request is touching the following templated files:

• .kokoro/mandatory-conformance.sh - .kokoro files are templated and should be updated in synthtool