performance-inefficient-vector-operation false-negatives when looping on multiple vectors

When a loop performs inefficient operations on multiple vectors, performance-inefficient-vector-operation does not emit a warning.

```c++
#include

int main() {
std::vector bob;
std::vector tom;

for (auto x = 0; x < 100; x++) {
bob.emplace_back(x);
tom.push_back(x);
}
}
```

does not emit any warnings. However, commenting out one or the other vectors from the same code does:

```c++
#include

int main() {
// std::vector bob;
std::vector tom;

for (auto x = 0; x < 100; x++) {
// bob.emplace_back(x);
tom.push_back(x);
}
}
```

```
:9:9: warning: 'push_back' is called inside a loop; consider pre-allocating the container capacity before the loop [performance-inefficient-vector-operation]
7 | for (auto x = 0; x < 100; x++) {
8 | // bob.emplace_back(x);
9 | tom.push_back(x);
| ^
1 warning generated.
```

Reproduce the warning behavior with the two-vector C++ example and the single-vector variant from the issue. Start by locating the implementation and tests for performance-inefficient-vector-operation, then add coverage showing that both inefficient operations are diagnosed while preserving the existing single-vector warning behavior.

Written by the indexing model from the issue text.