Use a single keypair for multiple instances

When I ran manila scenario tests, some tests failed due to
ssh key authentication. I noticed that tests with single
instance pass, however, tests with more than one instance
(e.g. "test_read_write_two_vms" test) fail.
I figured out that every instance initialization creates a
unique keypair.
An unnecessary resource duplication, when a single user boots
more than one instance. Depending on test flow this may also
cause keypair mismatch.

Change-Id: Ic685d1b9574daf7e6c9b90d5636f1b614a70b0da
Related-bug: #1858024
diff --git a/releasenotes/notes/bug-1858024-fa76d4c5b27f099b.yaml b/releasenotes/notes/bug-1858024-fa76d4c5b27f099b.yaml
new file mode 100644
index 0000000..b94e1c9
--- /dev/null
+++ b/releasenotes/notes/bug-1858024-fa76d4c5b27f099b.yaml
@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    Fixed bug #1858024. Define a signle key for multiple instances.
+    Currently every instance initialization creates a unique keypair.
+    An unnecessary resource duplication, when a single user boots more
+    than one instance.
+    Depending on test flow this may also cause keypair mismatch.