[per-stream state] Migrate GA connectors that implement custom read()

[brianjlai]

Most API source connectors should be able to start emitting per stream state by just updating to the latest version of the CDK once the changes are released on a version.

However, for any connectors that override the existing abstract_source.read() method, we explicitly continue to send them state in the legacy object format so that we don't break compatibility when it pulls the latest version of the CDK. For reference: https://github.com/airbytehq/airbyte/blob/master/airbyte-cdk/python/airbyte_cdk/sources/source.py#L80-L81

As part of migrating the connectors to per stream format, a couple connectors will require some changes to become compatible with the new format. The following GA connectors will be affected:

• source-google-sheets
• source-hubspot
• source-instagram
• source-salesforce