presubmit: add whitespace test in go (#3629)

Automatically submitted.

.presubmit/context

@@ -1,8 +0,0 @@
-#!/usr/bin/env bash
-
-echo "** presubmit/$(basename $0)"
-
-if grep -lr "golang.org/x/net/context" "$@"; then
-    echo "** presubmit/$(basename $0): please use std lib's 'context' instead"
-    exit 1
-fi

.presubmit/trailing-whitespace

@@ -1,7 +0,0 @@
-#!/usr/bin/env bash
-
-echo "** presubmit/$(basename $0)"
-
-if grep -r '[[:blank:]]$' "$@"; then
-    echo "** presubmit/$(basename $0): please remove any trailing white space"
-fi