Fixed test case failure

[MAT1018]

Fix cBioPortal/cbioportal#11445

Fixes:
• Used async/await for proper test execution.
• Increased timeout using jest.setTimeout(10000).
• Refactored sinon.stub to dynamically resolve session IDs.
• Ensured correct session sequencing using await new Promise(resolve => setTimeout(resolve, 100));.
• Restored stub after test execution to prevent interference.

Result:
• All tests passed (yarn test confirms no failures).
• Session handling now correctly reflects sequence execution.

Checks

• Has tests or has a separate issue that describes the types of test that should be created. If no test is included it should explicitly be mentioned in the PR why there is no test.
• The commit log is comprehensible. It follows 7 rules of great commit messages. For most PRs a single commit should suffice, in some cases multiple topical commits can be useful. During review it is ok to see tiny commits (e.g. Fix reviewer comments), but right before the code gets merged to master or rc branch, any such commits should be squashed since they are useless to the other developers. Definitely avoid merge commits, use rebase instead.
• Is this PR adding logic based on one or more clinical attributes? If yes, please make sure validation for this attribute is also present in the data validation / data loading layers (in backend repo) and documented in File-Formats Clinical data section!

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[alisman]

@MAT1018 thank you for this PR. unless I'm mistaken, the unit tests seemed to already be passing though. what prompted this change?

[MAT1018]

@alisman I am sorry. I had run all the test cases upon setting up the repo and found 1 test case failing so raised issue and PR with screenshots but now they seem to pass. Must have been my mistake, thank you for enlightening me.