chore(*) update envoy to 1.18.4

[bartsmykla]

Summary

It includes latest security patch for high severity cve: https://nvd.nist.gov/vuln/detail/CVE-2021-32779

Full changelog

no changelog

Issues resolved

no issue

Documentation

no documentation change

Testing

• Unit tests
• E2E tests
• Manual testing on Universal
• Manual testing on Kubernetes

Backwards compatibility

• Add backport-to-stable label if the code is backwards compatible. Otherwise, list breaking changes.

[codecov-commenter]

Codecov Report

Merging #2667 (7c7f264) into master (9419f21) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2667      +/-   ##
==========================================
- Coverage   51.97%   51.94%   -0.03%     
==========================================
  Files         871      871              
  Lines       49505    49505              
==========================================
- Hits        25730    25717      -13     
- Misses      21696    21710      +14     
+ Partials     2079     2078       -1     

Impacted Files	Coverage Δ
pkg/insights/components.go	70.00% <0.00%> (-30.00%)	⬇️
pkg/core/resources/store/customizable_store.go	77.77% <0.00%> (-11.12%)	⬇️
.../core/managers/apis/ratelimit/ratelimit_manager.go	35.48% <0.00%> (-9.68%)	⬇️
pkg/plugins/resources/memory/store.go	77.71% <0.00%> (-4.35%)	⬇️
pkg/core/resources/manager/cache.go	81.81% <0.00%> (-2.60%)	⬇️
pkg/insights/resyncer.go	66.16% <0.00%> (-1.51%)	⬇️
pkg/xds/generator/direct_access_proxy_generator.go	83.90% <0.00%> (+1.14%)	⬆️
app/kumactl/cmd/root.go	73.68% <0.00%> (+3.50%)	⬆️
pkg/core/bootstrap/autoconfig.go	54.46% <0.00%> (+8.03%)	⬆️

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