tests: add symlink for ubuntu hosts inventory

otherwise a bunch of jobs will fail like following:

```
 [WARNING]: Unable to parse /home/jenkins-build/build/workspace/ceph-ansible-nightly-luminous-ubuntu-container-stable-3.2-bluestore_lvm_osds/tests/functional/bs-lvm-osds/container/hosts-ubuntu as an inventory source
 [WARNING]: No inventory was parsed, only implicit localhost is available
 [WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit localhost does not match 'all'
```

Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>

diff --git a/tests/functional/add-osds/hosts-ubuntu b/tests/functional/add-osds/hosts-ubuntu
new file mode 120000 (symlink)
index 0000000..9b0b900
--- /dev/null
+++ b/tests/functional/add-osds/hosts-ubuntu
@@ -0,0 +1 @@
+hosts
\ No newline at end of file

diff --git a/tests/functional/bs-lvm-osds/hosts-ubuntu b/tests/functional/bs-lvm-osds/hosts-ubuntu
new file mode 120000 (symlink)
index 0000000..9b0b900
--- /dev/null
+++ b/tests/functional/bs-lvm-osds/hosts-ubuntu
@@ -0,0 +1 @@
+hosts
\ No newline at end of file

diff --git a/tests/functional/collocation/hosts-ubuntu b/tests/functional/collocation/hosts-ubuntu
new file mode 120000 (symlink)
index 0000000..9b0b900
--- /dev/null
+++ b/tests/functional/collocation/hosts-ubuntu
@@ -0,0 +1 @@
+hosts
\ No newline at end of file

diff --git a/tests/functional/lvm-batch/hosts-ubuntu b/tests/functional/lvm-batch/hosts-ubuntu
new file mode 120000 (symlink)
index 0000000..9b0b900
--- /dev/null
+++ b/tests/functional/lvm-batch/hosts-ubuntu
@@ -0,0 +1 @@
+hosts
\ No newline at end of file

diff --git a/tests/functional/lvm-osds/hosts-ubuntu b/tests/functional/lvm-osds/hosts-ubuntu
new file mode 120000 (symlink)
index 0000000..9b0b900
--- /dev/null
+++ b/tests/functional/lvm-osds/hosts-ubuntu
@@ -0,0 +1 @@
+hosts
\ No newline at end of file

diff --git a/tests/functional/shrink_osd/hosts-ubuntu b/tests/functional/shrink_osd/hosts-ubuntu
new file mode 120000 (symlink)
index 0000000..9b0b900
--- /dev/null
+++ b/tests/functional/shrink_osd/hosts-ubuntu
@@ -0,0 +1 @@
+hosts
\ No newline at end of file