Fix flaky e2e test

[MrSerth]

• Failed: https://github.com/openHPI/poseidon/actions/runs/9698681202/attempts/1
• Successful: https://github.com/openHPI/poseidon/actions/runs/9698681202/attempts/2

websocket_test.go:363: 
        Error Trace:    /home/runner/work/poseidon/poseidon/tests/e2e/websocket_test.go:363
                                    /home/runner/work/poseidon/poseidon/tests/e2e/websocket_test.go:170
                                    /home/runner/go/pkg/mod/github.com/stretchr/testify@v1.9.0/suite/suite.go:115
        Error:          Not equal: 
                        expected: 1
                        actual  : 0
        Test:           TestE2ETestSuite/TestCommandMakeEnvironmentVariables/0