Move example tree sequences to tsutil

Author: benjeffery

python/tests/test_balance_metrics.py

@@ -29,7 +29,7 @@
 
 import tests
 import tskit
-from tests.test_highlevel import get_example_tree_sequences
+from tests.tsutil import get_example_tree_sequences
 
 # ↑ See https://github.com/tskit-dev/tskit/issues/1804 for when
 # we can remove this.

python/tests/test_divmat.py

@@ -32,7 +32,7 @@
 
 import tskit
 from tests import tsutil
-from tests.test_highlevel import get_example_tree_sequences
+from tests.tsutil import get_example_tree_sequences
 
 # ↑ See https://github.com/tskit-dev/tskit/issues/1804 for when
 # we can remove this.

python/tests/test_extend_haplotypes.py

@@ -6,7 +6,7 @@
 import tests.test_wright_fisher as wf
 import tskit
 from tests import tsutil
-from tests.test_highlevel import get_example_tree_sequences
+from tests.tsutil import get_example_tree_sequences
 
 # ↑ See https://github.com/tskit-dev/tskit/issues/1804 for when
 # we can remove this.

python/tests/test_genotypes.py

@@ -37,7 +37,7 @@
 import tests.test_wright_fisher as wf
 import tests.tsutil as tsutil
 import tskit
-from tests.test_highlevel import get_example_tree_sequences
+from tests.tsutil import get_example_tree_sequences
 from tskit import exceptions
 from tskit.genotypes import allele_remap