Drop `ext_info` from `METAFLOW_VERSION` env var in `@batch` and `@kubernetes`

[savingoyal]

https://outerboundsco.slack.com/archives/C02116BBNTU/p1658246993734459 through chat.metaflow.org

[heysujal]

@savingoyal Not able to see it even after signing up on the workspace.

[saikonen]

additional context from the thread

• affects flows deployed with step-functions or argo-workflows, as these are the only ones setting the env var.
• ext_info only filled in when using metaflow extensions

[saikonen]

After testing this out, the issue should be fixed by #1329