chore(ci): no longer update sysdig chart on agent releases

[aroberts87]

What this PR does / why we need it:

the legacy sysdig chart is being deprecated, so we are removing the automation to automatically update the chart when new versions of the agent are released.

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• Title of the PR starts with type and scope, (e.g. feat(agent,node-analyzer,sysdig-deploy):)
• Chart Version bumped for the respective charts
• Variables are documented in the README.md (or README.tpl in some charts)
• Check GithubAction checks (like lint) to avoid merge-check stoppers
• All test files are added in the tests folder of their respective chart and have a "_test" suffix

Check Contribution guidelines in README.md for more insight.

[mavimo]

@aroberts87 I suppose we need to get rid of .github/workflows/update-operator.yaml as well since the operator expect a ne version of the chart when triggered.