Fixed DocumentAI flakey tests

[melinath]

Added a short sleep to test_check_destroy.

#17321 "broke" these tests by fixing the URL computation in test check destroy. I'm not able to reproduce the failure locally but I'm hopeful that adding a short sleep will help here (similar to #17465, which I was able to reproduce.)

Release Note Template for Downstream PRs (will be copied)

See Write release notes for guidance.

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes for commit 4357f0d:

Diff report

Your PR generated the following diffs in downstream repositories:

Repository	Diff Link	Changes
google provider	View Diff	2 files changed, 8 insertions(+), 2 deletions(-)
google-beta provider	View Diff	2 files changed, 8 insertions(+), 2 deletions(-)

Test report

Analytics

Total Tests	Passed	Skipped	Affected
5	5	0	0

Affected Service Packages

• documentai

Learn how VCR tests work

---

Step 1: Replaying Mode

🟢 All tests passed in Replaying mode! No Recording was needed.

View the build log

@melinath, @zli82016 VCR tests complete for 4357f0d!