### Proposed changes
 
This PR explicitly sets the `opttest.SkipInstall()` option for our yaml
tests. It is observed that the test framework/automation API is unable
successfully run `pulumi install` prior to the other pulumi operations.
This error was hit in the presubmit for
https://github.com/pulumi/pulumi-kubernetes/pull/3046, but went
unnoticed in the past due to the `TestTerraformConvert` installing the
right plugins before the other tests hit the installation step.

Manual validation:

- Deleted the local `~/.pulumi/plugin` folder
- Run the tests without the changes and notice the test errors
- Run the tests with the changes here and they pass

### Related issues (optional)

Fixes: #3048