Split py_binary into py_binary and py_library to avoid having py_binary in deps.

Having py_binary in deps is deprecated and will break in 19Q1.
[] for more details.

If this CL broke you, please fix forward by manually running
[]/devtools/python/janitor:lib_split_binary []

Tested:
    TAP --sample for global presubmit queue
    []

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=230359276

python/google/registry/scripts/BUILD

@@ -5,6 +5,12 @@ licenses(["notice"])  # Apache 2.0
 py_binary(
     name = "xml_to_index_yaml_translator",
     srcs = ["xml_to_index_yaml_translator.py"],
+    deps = [":xml_to_index_yaml_translator_lib"],
+)
+
+py_library(
+    name = "xml_to_index_yaml_translator_lib",
+    srcs = ["xml_to_index_yaml_translator.py"],
     deps = ["//python:python_directory_import"],
 )
 
@@ -16,5 +22,5 @@ py_test(
         "testdata/datastore-indexes.xml",
         "testdata/index.yaml",
     ],
-    deps = [":xml_to_index_yaml_translator"],
+    deps = [":xml_to_index_yaml_translator_lib"],
 )