chore: align all helm calls to use go tool

[shahar-h]

What this PR does / why we need it:

Replace bare helm commands with $(GO_TOOL) helm in helm.mk and kube.mk for consistency with the rest of the codebase. This ensures the project-pinned Helm version is used everywhere.

Which issue(s) this PR fixes:

N/A

Release Notes: No

[netlify]

✅ Deploy Preview for cerulean-figolla-1f9435 canceled.

Name	Link
🔨 Latest commit	96ee587
🔍 Latest deploy log	https://app.netlify.com/projects/cerulean-figolla-1f9435/deploys/69ceb409ee11ec000830a719

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.50%. Comparing base (b4b5cab) to head (96ee587).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8659      +/-   ##
==========================================
+ Coverage   74.46%   74.50%   +0.03%     
==========================================
  Files         243      243              
  Lines       38670    38670              
==========================================
+ Hits        28796    28810      +14     
+ Misses       7879     7867      -12     
+ Partials     1995     1993       -2     

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[shahar-h]

/retest

[shahar-h]

/retest