java: split declaration & assignment: fix for very broken code (IDEA-254385)

forcePsiPostprocessAndRestoreElement may invalidate variable initializer

GitOrigin-RevId: 31b99804e5603cff36494ecbf9f98c1716b13d22

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/splitDeclaration/beforeBroken.java

@@ -0,0 +1,10 @@
+// "Split into declaration and assignment" "true"
+
+class Foo {
+  {
+    <caret>int fieldIndexes = getFieldIndexes(Hellonew String[]{""});
+  }
+  public int getFieldIndexes(String[] columns) {
+    return 0;
+  }
+}