Don't enable the dstat service in CI jobs

We still are seeing regular job failures because the pcp package fails
to install. Assume that we can still enable it on demand when someone
needs to debug specific job issues, let us just disable it by default.

Related-Bug: 1943184
Signed-off-by: Dr. Jens Harbott <harbott@osism.tech>
Change-Id: I32ef8038e21c818623db9389588b3c6d3f98dcad
diff --git a/.zuul.yaml b/.zuul.yaml
index b5ab127..e5ef7ee 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -432,7 +432,7 @@
         PUBLIC_BRIDGE_MTU: '{{ external_bridge_mtu }}'
       devstack_services:
         # Shared services
-        dstat: true
+        dstat: false
         etcd3: true
         memory_tracker: true
         mysql: true
@@ -441,7 +441,7 @@
       subnode:
         devstack_services:
           # Shared services
-          dstat: true
+          dstat: false
           memory_tracker: true
         devstack_localrc:
           # Multinode specific settings
@@ -507,7 +507,7 @@
         # Core services enabled for this branch.
         # This list replaces the test-matrix.
         # Shared services
-        dstat: true
+        dstat: false
         etcd3: true
         memory_tracker: true
         mysql: true
@@ -557,7 +557,7 @@
           # Core services enabled for this branch.
           # This list replaces the test-matrix.
           # Shared services
-          dstat: true
+          dstat: false
           memory_tracker: true
           tls-proxy: true
           # Nova services