#### What this PR does / why we need it:
Remove unused GitHub workflow files that are either disabled or related
to legacy chaos/deploy automation, and clean up README links that
pointed to removed workflows.
Removed workflows:
- `.github/workflows/delete_comments.yaml`
- `.github/workflows/deploy-test.yaml`
- `.github/workflows/io-latency-chaos-test.yaml`
- `.github/workflows/mem-stress-chaos-test.yaml`
- `.github/workflows/network-latency-chaos-test.yaml`
- `.github/workflows/network-partition-chaos-test.yaml`
- `.github/workflows/pod-failure-chaos-test.yaml`
- `.github/workflows/pod-kill-chaos-test-kafka-version.yaml`
- `.github/workflows/pod-kill-chaos-test.yaml`
- `.github/workflows/simd-compatibility-test.yaml`
#### Which issue(s) this PR fixes:
issue: #49574
#### Special notes for your reviewer:
This is a GitHub Actions cleanup only. The removed workflow file names
no longer have references under `.github` or `tests`.
#### Verification:
- `git diff --check`
- `rg -n
"delete_comments|deploy-test\.yaml|io-latency-chaos-test|mem-stress-chaos-test|network-latency-chaos-test|network-partition-chaos-test|pod-failure-chaos-test|pod-kill-chaos-test|simd-compatibility-test"
.github tests` returned no matches
Signed-off-by: zhuwenxing <wenxing.zhu@zilliz.com>