Fix #15034 FN arrayIndexOutOfBounds (ternary in subfunction) - #8856

This is an AI review. Take it with a grain of salt and feel free to reject it by resolving the comment.

I confirmed that this suppression is needed because of the PR. With selfcheck's options (--check-level=exhaustive --library=cppcheck-lib ...), the merge base gives no warning here, while this PR gives Possible null pointer dereference: fredScope. It is a false positive, since assert_() throws when the condition fails. The cause is that the removed "condition depends on only one variable" guard in setTokenValue() used to drop the nullptr from (it == db->scopeList.end()) ? nullptr : &*it, because the condition contains a function call. So user code with the same "ternary + throwing check" pattern will now also hit #9747.

To get a feel for how often that happens, I compared warnings for the merge base and the PR on lib/, cli/, test/cfg/, samples/, testsymboldatabase.cpp and testvalueflow.cpp (normal check level, style/warning/portability/performance, inconclusive). Both gave exactly the same 2407 warnings, so it doesn't look widespread. Some correlated-ternary probes such as d = (a > b) ? 0 : a - b; if (a > b) return 0; return 10 / d; also stayed silent. Just mentioning it so the trade-off is a conscious one.