C++: SloppyGlobal: Don't alert on template instantiations, only the template

[igfoo]

Alerting on instantiations essentially just gives us duplicate alerts

[Copilot]

Pull Request Overview

This PR improves the SloppyGlobal CodeQL query to avoid duplicate alerts when checking for poorly named global variables. The change ensures that only template variable declarations are flagged, not their individual instantiations.

Key changes:

• Modified the SloppyGlobal query logic to exclude VariableTemplateInstantiation instances
• Added test cases with template variables to verify the behavior
• Updated expected results to show only template declarations are reported

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
cpp/ql/src/Best Practices/SloppyGlobal.ql	Added condition to exclude variable template instantiations from alerts
cpp/ql/test/query-tests/Best Practices/SloppyGlobal/main.cpp	Added test cases with template variables and their usage
cpp/ql/test/query-tests/Best Practices/SloppyGlobal/SloppyGlobal.expected	Updated expected results to include new test cases

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[jketema]

LGTM. One nit and two further things that need to happen:

• Could you please start a traced DCA experiment on this?
• Could you please add a change note?