ci(lts-2.21): bump deprecated GitHub Actions (checkout v7, codeql v3, setup-helm v5)

[guimard]

Same action bumps as the master PR, for the lts-2.21 branch (which still had
22× actions/checkout@v3 plus 3× @v4).

Action	Before	After
actions/checkout	v3 / v4	v7
github/codeql-action/upload-sarif	v2 / v3	v3
azure/setup-helm	v4	v5

Resolves the deprecated-action warnings (incl. the transitive
actions/upload-artifact@v4 via codeql-action).

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