ci: add duration parameter for ci workflow.

[OscarDDD]

Context

Closes SAP/ai-sdk-python-backlog#35.

What this PR does and why it is needed

The integration tests (gen) pipeline can take over an hour, making it hard to identify which individual tests are the bottleneck. This PR adds --durations=0 to the pytest command in the integration-tests-gen CI job, which reports the execution time of every individual test at the end of the pipeline run (sorted slowest-first). This makes it immediately visible which tests are slow, enabling informed decisions on how to optimize the pipeline.

Definition of Done

• [ ☑️] Code is tested (Unit, Integration, E2E) - the flag is a built-in pytest feature, verified locally against the real integration test suite; timing output confirmed in the run results
• [ ☑️] Error handling created / updated & covered by the tests above — N/A, no error handling changes needed for a reporting flag
• [ ☑️] Documentation updated - N/A, this is a CI-only change with no public API impact
• [ ☑️] Aligned with JS/TS and Java SDK — N/A, CI-internal change
• [ ☑️] Release notes — N/A, CI-internal change, no user-facing impact

Example output

[yamaceay]

lgtm @alpkom