Python: Update all metrics-dependant queries

The ones that no longer require points-to no longer import
`LegacyPointsTo`. The ones that do use the specific
`...MetricsWithPointsTo` classes that are applicable.

python/ql/src/Summary/LinesOfCode.ql

@@ -10,6 +10,5 @@
  */
 
 import python
-private import LegacyPointsTo
 
 select sum(ModuleMetrics m | | m.getNumberOfLinesOfCode())

python/ql/src/Summary/LinesOfUserCode.ql

@@ -14,7 +14,6 @@
 
 import python
 import semmle.python.filters.GeneratedCode
-private import LegacyPointsTo
 
 select sum(ModuleMetrics m |
     exists(m.getFile().getRelativePath()) and