Fix targeting hosts to 'localhost' instead of 'all'

This patch fixes the targeting hosts for the validations which should be
executed locally.

Rationale: When those validations are executed in the TripleO world,
they are executed on all the nodes including the Overcloud nodes. For
instance, check-ram and check-cpu validations check the Red Hat
recommendations for the Undercloud only and shouldn't be checking the
Overcloud nodes.

Change-Id: Icca554ea4392c3b0b572b27c2e2370b11f8013d7
Signed-off-by: Gael Chamoulaud (Strider) <gchamoul@redhat.com>

validations_common/playbooks/512e.yaml

@@ -1,5 +1,5 @@
 ---
-- hosts: all
+- hosts: localhost
   vars:
     metadata:
       name: Advanced Format 512e Support

validations_common/playbooks/check-cpu.yaml

@@ -1,5 +1,5 @@
 ---
-- hosts: all
+- hosts: localhost
   gather_facts: false
   vars:
     metadata:

validations_common/playbooks/check-disk-space-pre-upgrade.yaml

@@ -1,5 +1,5 @@
 ---
-- hosts: all
+- hosts: localhost
   vars:
     metadata:
       name: Verify server fits the disk space requirements to perform an upgrade

validations_common/playbooks/check-disk-space.yaml

@@ -1,5 +1,5 @@
 ---
-- hosts: all
+- hosts: localhost
   vars:
     metadata:
       name: Verify server fits the disk space requirements

validations_common/playbooks/check-ftype.yaml

@@ -1,5 +1,5 @@
 ---
-- hosts: all
+- hosts: localhost
   vars:
     metadata:
       name: XFS ftype check

validations_common/playbooks/check-ram.yaml

@@ -1,5 +1,5 @@
 ---
-- hosts: all
+- hosts: localhost
   gather_facts: false
   vars:
     metadata:

validations_common/playbooks/check-selinux-mode.yaml

@@ -1,5 +1,5 @@
 ---
-- hosts: all
+- hosts: localhost
   gather_facts: false
   vars:
     metadata:

validations_common/playbooks/dns.yaml

@@ -1,5 +1,5 @@
 ---
-- hosts: all
+- hosts: localhost
   vars:
     metadata:
       name: Verify DNS

validations_common/playbooks/no-op.yaml

@@ -1,5 +1,5 @@
 ---
-- hosts: all
+- hosts: localhost
   vars:
     metadata:
       name: NO-OP validation

validations_common/playbooks/ntp.yaml

@@ -1,5 +1,5 @@
 ---
-- hosts: overcloud
+- hosts: localhost
   vars:
     metadata:
       name: Verify all deployed servers have their clock synchronised