Java: `InstanceInitializer` body control flow is wrong

### Version
CodeQL CLI 2.5.1

### Description
It appears the body of `InstanceInitializer` is incorrect (and therefore its control flow is wrong). Instead of having the same order as the Java bytecode it always orders field initializations to the beginning, followed by the explicit initializer blocks.
`StaticInitializer` does not seem to be affected.

### Example
Create a database from the following Java source file:
```java
class InitOrder {
static String printStr(String s) {
System.out.println(s);
return s;
}

static String s1 = printStr("static field 1");
static {
System.out.println("static block 1");
}

static String s2 = printStr("static field 2");
static {
System.out.println("static block 2");
}

String i1 = printStr("instance field 1");
{
System.out.println("instance block 1");
}

String i2 = printStr("instance field 2");
{
System.out.println("instance block 2");
}

public InitOrder() {
System.out.println("Constructor");
}

public static void main(String... args) {
new InitOrder();
}
}
```

Run the following CodeQL query (thanks intrigus-lgtm for pointing me to the path explanations):
```ql
/**
* @kind path-problem
*/

import java

query predicate edges(ControlFlowNode a, ControlFlowNode b) { a.getASuccessor() = b }

from ControlFlowNode start, ControlFlowNode end
where
not exists(start.getAPredecessor())
and not exists(end.getASuccessor())
and edges+(start, end)
select end, start, end, "Control flow path"
```

You will notice that it shows that `"instance field 1"` and `"instance field 2"` will be processed first before the explicit initializer blocks.
Compare that with the `javap -v` output of the `.class` file, or the result of running `java InitOrder.java`:
```
instance field 1
instance block 1
instance field 2
instance block 2
```