formatted gcloud completion and used helper function

clean_files.txt

@@ -63,6 +63,7 @@ completion/available/cargo.completion.bash
 completion/available/conda.completion.bash
 completion/available/consul.completion.bash
 completion/available/docker.completion.bash
+completion/available/gcloud.completion.bash
 completion/available/knife.completion.bash
 completion/available/packer.completion.bash
 completion/available/pipx.completion.bash

completion/available/gcloud.completion.bash

@@ -1,9 +1,13 @@
-#/usr/bin/env bash
+# shellcheck shell=bash
 # Bash completion for Google Cloud SDK
 
-if which gcloud >/dev/null 2>&1; then
+if _command_exists gcloud; then
+	# get install path
 	GOOGLE_SDK_ROOT=${GOOGLE_SDK_ROOT:-$(gcloud info --format="value(installation.sdk_root)")}
-  for i in $(ls ${GOOGLE_SDK_ROOT}/*.bash.inc); do
-    source $i
+
+	# source all the bash completion file that are available
+	for i in "${GOOGLE_SDK_ROOT}"/*.bash.inc; do
+		# shellcheck disable=SC1090
+		source "$i"
 	done
 fi