Unskip some tests that appear to pass (#15567)

These mostly date back to https://github.com/python/mypy/pull/4369 There
are also some skipped tests in here that fail that I don't touch
diff --git a/mypy/test/testsubtypes.py b/mypy/test/testsubtypes.py
index c76a34f..464f64d 100644
--- a/mypy/test/testsubtypes.py
+++ b/mypy/test/testsubtypes.py
@@ -2,7 +2,7 @@
 
 from mypy.nodes import CONTRAVARIANT, COVARIANT, INVARIANT
 from mypy.subtypes import is_subtype
-from mypy.test.helpers import Suite, skip
+from mypy.test.helpers import Suite
 from mypy.test.typefixture import InterfaceTypeFixture, TypeFixture
 from mypy.types import Instance, TupleType, Type, UnpackType
 
@@ -69,7 +69,6 @@
         self.assert_equivalent(self.fx.f, self.fx.f)
         self.assert_not_subtype(self.fx.a, self.fx.f)
 
-    @skip
     def test_generic_interface_subtyping(self) -> None:
         # TODO make this work
         fx2 = InterfaceTypeFixture()
diff --git a/mypy/test/testtypes.py b/mypy/test/testtypes.py
index 5f6943d..246350d 100644
--- a/mypy/test/testtypes.py
+++ b/mypy/test/testtypes.py
@@ -899,13 +899,11 @@
         self.assert_join(ov(c(fx.a, fx.a), c(fx.b, fx.b)), c(any, fx.b), c(any, fx.b))
         self.assert_join(ov(c(fx.a, fx.a), c(any, fx.b)), c(fx.b, fx.b), c(any, fx.b))
 
-    @skip
     def test_join_interface_types(self) -> None:
         self.assert_join(self.fx.f, self.fx.f, self.fx.f)
         self.assert_join(self.fx.f, self.fx.f2, self.fx.o)
         self.assert_join(self.fx.f, self.fx.f3, self.fx.f)
 
-    @skip
     def test_join_interface_and_class_types(self) -> None:
         self.assert_join(self.fx.o, self.fx.f, self.fx.o)
         self.assert_join(self.fx.a, self.fx.f, self.fx.o)
@@ -1180,7 +1178,6 @@
         self.assert_meet(self.fx.e, self.fx.e2, self.fx.nonet)
         self.assert_meet(self.fx.e2, self.fx.e3, self.fx.nonet)
 
-    @skip
     def test_meet_with_generic_interfaces(self) -> None:
         fx = InterfaceTypeFixture()
         self.assert_meet(fx.gfa, fx.m1, fx.m1)