E2E test fix: web ide spec

What does this MR do and why?

Backports a test fix which is failing in all 17.9 pipelines

Original failure issue: https://gitlab.com/gitlab-org/gitlab/-/issues/519686#note_2365167954

Test passing in this MR: https://gitlab.com/gitlab-org/gitlab/-/pipelines/1688774270

Example failing pipline: !182632 (comment 2366965909)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• This MR is backporting a bug fix, documentation update, or spec fix, previously merged in the default branch.
• The MR that fixed the bug on the default branch has been deployed to GitLab.com (not applicable for documentation or spec changes).
• This MR has a severity label assigned (if applicable).
• Set the milestone of the merge request to match the target backport branch version.
• This MR has been approved by a maintainer (only one approval is required).
• Ensure the e2e:test-on-omnibus-ee job has either succeeded or been approved by a Software Engineer in Test.

Note to the merge request author and maintainer

If you have questions about the patch release process, please:

• Refer to the patch release runbook for engineers and maintainers for guidance.
• Ask questions on the #releases Slack channel (internal only).