[taskcluster] Use string.capitalize() rather than custom utility function

taskcluster/fenix_taskgraph/transforms/build.py

@@ -12,7 +12,6 @@ import datetime
 
 from taskgraph.transforms.base import TransformSequence
 from fenix_taskgraph.gradle import get_variant
-from fenix_taskgraph.util import upper_case_first_letter
 
 
 transforms = TransformSequence()
@@ -72,7 +71,7 @@ def build_gradle_command(config, tasks):
 
         task["run"]["gradlew"] = [
             "clean",
-            "assemble{}".format(upper_case_first_letter(variant_config["name"]))
+            "assemble{}".format(variant_config["name"].capitalize()),
         ]
 
         yield task

taskcluster/fenix_taskgraph/util.py

@@ -1,11 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-from __future__ import absolute_import, print_function, unicode_literals
-
-import re
-
-
-def upper_case_first_letter(string):
-    return string[0].upper() + string[1:]