Increase nova-cloud-controller RAM in func tests

Recent test run(s) have shown memory exhaustion on the nova
cloud controller units. This exhibits itself as the controller
dropping messages from the compute nodes and logging messages like:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/oslo_service/threadgroup.py", line 268, in _perform_action_on_threads
  File "/usr/lib/python3/dist-packages/oslo_service/threadgroup.py", line 342, in <lambda>
    lambda x: x.wait(),
  File "/usr/lib/python3/dist-packages/oslo_service/threadgroup.py", line 61, in wait
    return self.thread.wait()
  File "/usr/lib/python3/dist-packages/eventlet/greenthread.py", line 180, in wait
    return self._exit_event.wait()
  File "/usr/lib/python3/dist-packages/eventlet/event.py", line 125, in wait
    result = hub.switch()
  File "/usr/lib/python3/dist-packages/eventlet/hubs/hub.py", line 298, in switch
    return self.greenlet.switch()
  File "/usr/lib/python3/dist-packages/eventlet/hubs/hub.py", line 350, in run
    self.wait(sleep_time)
  File "/usr/lib/python3/dist-packages/eventlet/hubs/poll.py", line 80, in wait
    presult = self.do_poll(seconds)
  File "/usr/lib/python3/dist-packages/eventlet/hubs/epolls.py", line 31, in do_poll
    return self.poll.poll(seconds)
MemoryError

to the nova-conductor log.

It seems very likely this issue is specific to Bionic Stein so it
may be a little wasteful to have increased the memory allocation
for all the bundles but I think consistancy between the bundles is
more important.

Change-Id: I2d45acadcd221786513c49256f087114a985e74f

tests/bundles/bionic-queens.yaml

@@ -11,7 +11,8 @@ machines:
   3: {}
   4: {}
   5: {}
-  6: {}
+  6:
+    constraints: "mem=4G"
   7:
     constraints: "root-disk=20G mem=4G"
   8:

tests/bundles/bionic-rocky.yaml

@@ -11,7 +11,8 @@ machines:
   3: {}
   4: {}
   5: {}
-  6: {}
+  6:
+    constraints: "mem=4G"
   7:
     constraints: "root-disk=20G mem=4G"
   8:

tests/bundles/bionic-stein.yaml

@@ -11,7 +11,8 @@ machines:
   3: {}
   4: {}
   5: {}
-  6: {}
+  6:
+    constraints: "mem=4G"
   7:
     constraints: "root-disk=20G mem=4G"
   8:

tests/bundles/bionic-train.yaml

@@ -11,7 +11,8 @@ machines:
   3: {}
   4: {}
   5: {}
-  6: {}
+  6:
+    constraints: "mem=4G"
   7:
     constraints: "root-disk=20G mem=4G"
   8:

tests/bundles/bionic-ussuri.yaml

@@ -11,7 +11,8 @@ machines:
   3: {}
   4: {}
   5: {}
-  6: {}
+  6:
+    constraints: "mem=4G"
   7:
     constraints: "root-disk=20G mem=4G"
   8:

tests/bundles/focal-ussuri.yaml

@@ -15,7 +15,8 @@ machines:
   5: {}
   6: {}
   7: {}
-  8: {}
+  8:
+    constraints: "mem=4G"
   9:
     constraints: "root-disk=20G mem=4G"
   10:

tests/bundles/focal-victoria.yaml

@@ -15,7 +15,8 @@ machines:
   5: {}
   6: {}
   7: {}
-  8: {}
+  8:
+    constraints: "mem=4G"
   9:
     constraints: "root-disk=20G mem=4G"
   10:

tests/bundles/focal-wallaby.yaml

@@ -15,7 +15,8 @@ machines:
   5: {}
   6: {}
   7: {}
-  8: {}
+  8:
+    constraints: "mem=4G"
   9:
     constraints: "root-disk=20G mem=4G"
   10:

tests/bundles/groovy-victoria.yaml

@@ -15,7 +15,8 @@ machines:
   5: {}
   6: {}
   7: {}
-  8: {}
+  8:
+    constraints: "mem=4G"
   9:
     constraints: "root-disk=20G mem=4G"
   10:

tests/bundles/hirsute-wallaby.yaml

@@ -15,7 +15,8 @@ machines:
   5: {}
   6: {}
   7: {}
-  8: {}
+  8:
+    constraints: "mem=4G"
   9:
     constraints: "root-disk=20G mem=4G"
   10:

tests/bundles/trusty-mitaka.yaml

@@ -11,7 +11,8 @@ machines:
   3: {}
   4: {}
   5: {}
-  6: {}
+  6:
+    constraints: "mem=4G"
   7:
     constraints: "root-disk=20G mem=4G"
   8:

tests/bundles/xenial-mitaka.yaml

@@ -11,7 +11,8 @@ machines:
   3: {}
   4: {}
   5: {}
-  6: {}
+  6:
+    constraints: "mem=4G"
   7:
     constraints: "root-disk=20G mem=4G"
   8:

tests/bundles/xenial-ocata.yaml

@@ -11,7 +11,8 @@ machines:
   3: {}
   4: {}
   5: {}
-  6: {}
+  6:
+    constraints: "mem=4G"
   7:
     constraints: "root-disk=20G mem=4G"
   8:

tests/bundles/xenial-pike.yaml

@@ -11,7 +11,8 @@ machines:
   3: {}
   4: {}
   5: {}
-  6: {}
+  6:
+    constraints: "mem=4G"
   7:
     constraints: "root-disk=20G mem=4G"
   8:

tests/bundles/xenial-queens.yaml

@@ -11,7 +11,8 @@ machines:
   3: {}
   4: {}
   5: {}
-  6: {}
+  6:
+    constraints: "mem=4G"
   7:
     constraints: "root-disk=20G mem=4G"
   8: