Use printf for skip_action

printf is posix compatible and works with all shell. echo -n does not
work with yash and is not posix compatible.

Add test for skipping expand_root

lib/tiny-cloud/init-common

@@ -25,5 +25,5 @@ skip_action() {
 
     # action not in the skip list?
     echo "$SKIP_INIT_ACTIONS" | grep -Eq "\b$action\b" || return 1
-    echo -n " SKIPPING"
+    printf " SKIPPING"
 }

tests/init-early.test

@@ -7,7 +7,8 @@ export MOCK=echo
 
 init_tests \
 	expand_root \
-	expand_root_partition
+	expand_root_partition \
+	expand_root_skip
 
 PROVIDERS="aws azure gcp nocloud oci"
 
@@ -49,3 +50,17 @@ expand_root_partition_body() {
 	done
 }
 
+expand_root_skip_body() {
+	fake_bin test-expand-root <<-EOF
+		#!/bin/sh
+		SKIP_INIT_ACTIONS=expand_root
+		. "$srcdir"/lib/tiny-cloud/init-early
+		expand_root
+	EOF
+	for provider in $PROVIDERS; do
+		CLOUD="$provider" atf_check \
+			-o match:'^ SKIPPING$' \
+			test-expand-root
+	done
+}
+