Make conftest more robust

[thctamm]

Changes

1. Make checking for serverless_comput_id more robust since that field does not exist on serverless client v1 and fill throw an error right now otherwise.
2. Add the test path to sys.path

Why

This will make the example test compatible with the upcoming workspace unit testing feature.

Tests

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Inputs:

• PR number: 4295
• Commit SHA: 970ebbaae49a134bd72607b71a4936fbb8edab29

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