Python: Fix query tests

Mostly just adding `private import LegacyPointsTo`. Sometimes getting
rid of other imports that are superceded by that module.

python/ql/src/Expressions/IsComparisons.qll

@@ -2,8 +2,6 @@
 
 import python
 private import LegacyPointsTo
-private import semmle.python.objects.ObjectInternal
-private import semmle.python.objects.ObjectAPI
 
 /** Holds if the comparison `comp` uses `is` or `is not` (represented as `op`) to compare its `left` and `right` arguments. */
 predicate comparison_using_is(Compare comp, ControlFlowNode left, Cmpop op, ControlFlowNode right) {

python/ql/src/Expressions/NonPortableComparisonUsingIs.ql

@@ -13,6 +13,7 @@
 
 import python
 import IsComparisons
+private import LegacyPointsTo
 
 from Compare comp, Cmpop op, ClassValue c
 where

python/ql/src/Expressions/RedundantComparison.qll

@@ -1,6 +1,7 @@
 /** Helper functions for queries that test redundant comparisons. */
 
 import python
+private import LegacyPointsTo
 
 /** A comparison where the left and right hand sides appear to be identical. */
 class RedundantComparison extends Compare {

python/ql/src/Expressions/WrongNameForArgumentInCall.ql

@@ -16,6 +16,7 @@
 
 import python
 import Expressions.CallArgs
+private import LegacyPointsTo
 
 from Call call, FunctionObject func, string name
 where

python/ql/src/Expressions/WrongNumberArgumentsForFormat.ql

@@ -15,7 +15,6 @@
 
 import python
 import LegacyPointsTo
-import semmle.python.objects.ObjectInternal
 import semmle.python.strings
 
 predicate string_format(BinaryExpr operation, StringLiteral str, Value args, AstNode origin) {

python/ql/src/Expressions/WrongNumberArgumentsInCall.ql

@@ -13,6 +13,7 @@
  */
 
 import python
+private import LegacyPointsTo
 import CallArgs
 
 from Call call, FunctionValue func, string too, string should, int limit