test: remove unused expectSession variable

[dsxack]

Related issue

The merge request does not relate to any issue, just remove unused variable in tests.

Proposed changes

The merge request does not propose any change.

Checklist

• I have read the contributing guidelines.
• I have read the security policy.
• I confirm that this pull request does not address a security
  vulnerability. If this pull request addresses a security. vulnerability, I
  confirm that I got green light (please contact
  security@ory.sh) from the maintainers to push
  the changes.
• I have added tests that prove my fix is effective or that my feature
  works.
• I have added or changed the documentation.

[CLAassistant]

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[aeneasr]

Awesome 🎉

Thank you for your contribution!