gha: Set Zizmor check as non-required

As a consequence of moving away from Advanced Security for Zizmor, it now
checks the entire codebase and will error out on this PR and future.

To be reverted once we address all Zizmor findings in a future PR.

Signed-off-by: Aurélien Bombo <abombo@microsoft.com>

tools/testing/gatekeeper/required-tests.yaml

@@ -6,7 +6,8 @@ required_tests:
   - Shellcheck required / shellcheck-required
   # TODO: cargo-deny-runner.yaml not yet treated as conditional
   - Cargo Crates Check Runner / cargo-deny-runner
-  - GHA security analysis / zizmor
+  # TODO: Reestablish when we've eliminated all Zizmor findings.
+  # - GHA security analysis / zizmor
 
 required_regexps:
   # Always required regexps