Use global initializer in pack regression

Exercise the empty and non-empty pack calls from a global initializer rather than main, and use generic names for the helper and pack.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: jketema

cpp/ql/test/query-tests/Best Practices/Unused Entities/UnusedStaticVariables/UnusedStaticVariables.expected

@@ -2,4 +2,4 @@
 | test.cpp:8:12:8:21 | staticVar6 | Static variable staticVar6 is never read. |
 | test.cpp:10:11:10:19 | constVar8 | Static variable constVar8 is never read. |
 | test.cpp:12:12:12:22 | staticVar10 | Static variable staticVar10 is never read. |
-| test.cpp:53:25:53:39 | restrictionPack | Static variable restrictionPack is never read. |
+| test.cpp:53:25:53:30 | values | Static variable values is never read. |

cpp/ql/test/query-tests/Best Practices/Unused Entities/UnusedStaticVariables/test.cpp

@@ -50,12 +50,9 @@ struct WithDestructor
 static WithConstructor constructed; // GOOD (constructor has a side effect)
 static WithDestructor destructed; // GOOD (destructor has a side effect)
 
-static auto All(auto... restrictionPack) // $ SPURIOUS: Alert
+static auto sum(auto... values) // $ SPURIOUS: Alert
 {
-	return (0U + ... + static_cast<unsigned>(restrictionPack));
+	return (0U + ... + static_cast<unsigned>(values));
 }
 
-int main()
-{
-	return All() + All(2U);
-}
+unsigned result = sum() + sum(2U);