FIR, Assign plugin: Update for KT-54648

plugins/assign-plugin/testData/diagnostics/otherOperators.fir.kt

@@ -50,6 +50,6 @@ fun `should not effect error reporting for other operators`() {
     task<!NO_SET_METHOD!>[0]<!> = StringProperty("Fail")
 
     // a.get(i) = b should not be translated to a.get(i).assign(b)
-    task.<!FUNCTION_CALL_EXPECTED!>get<!>(0) = StringProperty("Fail")
-    nullTask?.<!FUNCTION_CALL_EXPECTED!>get<!>(0) = StringProperty("Fail")
+    task.<!VARIABLE_EXPECTED!>get(0)<!> = StringProperty("Fail")
+    nullTask?.<!VARIABLE_EXPECTED!>get(0)<!> = StringProperty("Fail")
 }

plugins/assign-plugin/testData/diagnostics/plusAssignPrecedence.fir.kt

@@ -96,7 +96,7 @@ fun box(): String {
     task.valInput <!UNRESOLVED_REFERENCE!>+=<!> "K"
     task.varInput <!UNRESOLVED_REFERENCE!>+=<!> "K"
 
-    task.<!VAL_REASSIGNMENT!>valInputWithPlus<!> += "K"
+    task.valInputWithPlus += "K"
 
     task.varInputWithPlusAndPlusAssign <!ASSIGN_OPERATOR_AMBIGUITY!>+=<!> "K"