[deps] Update module github.com/cilium/cilium to v1.18.4 [SECURITY]

[AshleyDumaine]

See linode/linode-cloud-controller-manager#496 (comment)

What this PR does / why we need it:

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

TODOs:

• squashed commits
• includes documentation
• adds unit tests
• adds or updates e2e tests

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 66.64%. Comparing base (1de86d2) to head (8fc790e).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #963   +/-   ##
=======================================
  Coverage   66.64%   66.64%           
=======================================
  Files          71       71           
  Lines        6352     6352           
=======================================
  Hits         4233     4233           
  Misses       1820     1820           
  Partials      299      299           

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