[Automated] Update net-istio nightly

[knative-automation]

/assign @knative/serving-writers /cc @knative/serving-writers

Produced via:

for x in net-istio.yaml; do
  curl https://storage.googleapis.com/knative-nightly/net-istio/latest/$x > ${GITHUB_WORKSPACE}/./third_party/istio-latest/$x
done

Details:

bumping knative.dev/net-istio a8bc624...f55ab3c:
  > f55ab3c preserve appropriate header matching when creating the virtualservice (# 1349)

[knative-prow[bot]]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 84.58%. Comparing base (b41a9e3) to head (1a01ca8).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #15406 +/- ## ========================================== + Coverage 84.55% 84.58% +0.02% ========================================== Files 219 219 Lines 13587 13587 ========================================== + Hits 11489 11493 +4 + Misses 1730 1726 -4 Partials 368 368 ```

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