test: deflake request queue aliases e2e test

[vdusek]

test_rq_aliases intermittently failed after the Actor reboot. The platform's batch-add endpoint is best-effort and can return a request as unprocessed; the singular add_request does not retry it (unlike add_requests), so the request was silently dropped and the post-reboot fetch_next_request returned None, failing the in-Actor assertion and the run.

This switches the two pre-reboot adds to add_requests, which retries unprocessed requests, so the requests reliably survive the reboot. Test-only change, mirroring the sibling deflake in #991.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.51%. Comparing base (726620b) to head (998230d).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1000      +/-   ##
==========================================
- Coverage   90.54%   90.51%   -0.04%     
==========================================
  Files          49       49              
  Lines        3132     3132              
==========================================
- Hits         2836     2835       -1     
- Misses        296      297       +1     

Flag	Coverage Δ
e2e	36.14% <ø> (ø)
integration	57.12% <ø> (-0.04%)	⬇️
unit	79.27% <ø> (ø)

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[vdusek]

If this is the intended behavior, we should just stabilize the test. If not, we should consider updating the add_request method (Apify storage client).