Wire circuit breaker into vsphere provider public methods

Without this change, the circuit breaker was initialized in base.rb
but never called in the vsphere provider, so vSphere API failures
(TCP timeouts, connection errors) would not trip the circuit open.

Changes:
- Add with_circuit_breaker helper that calls @circuit_breaker.call
  if circuit_breaker is configured, otherwise yields directly
- Wrap vms_in_pool, get_vm, create_vm, destroy_vm, get_vm_ip_address
  with with_circuit_breaker so vSphere failures trip the circuit
- Replace 'return' with 'next' inside blocks where needed to ensure
  circuit breaker on_success is properly called on partial results

This prevents cascading failures: once the circuit opens after
failure_threshold errors, subsequent calls fail fast (CircuitOpenError)
instead of waiting for the full TCP timeout (~18s per pool).

Resolves: P4DEVOPS-9438

lib/vmpooler/providers/vsphere.rb

@@ -186,16 +186,18 @@ module Vmpooler
 
         def vms_in_pool(pool_name)
           vms = []
+          with_circuit_breaker do
             @connection_pool.with_metrics do |pool_object|
               connection = ensured_vsphere_connection(pool_object)
               folder_object = find_vm_folder(pool_name, connection)
 
-            return vms if folder_object.nil?
+              next if folder_object.nil?
 
               folder_object.childEntity.each do |vm|
                 vms << { 'name' => vm.name } if vm.is_a? RbVmomi::VIM::VirtualMachine
               end
             end
+          end
           vms
         end
 
@@ -305,13 +307,15 @@ module Vmpooler
 
         def get_vm(pool_name, vm_name)
           vm_hash = nil
+          with_circuit_breaker do
             @connection_pool.with_metrics do |pool_object|
               connection = ensured_vsphere_connection(pool_object)
               vm_object = find_vm(pool_name, vm_name, connection)
-            return vm_hash if vm_object.nil?
+              next if vm_object.nil?
 
               vm_hash = generate_vm_hash(vm_object, pool_name)
             end
+          end
           vm_hash
         end
 
@@ -320,6 +324,7 @@ module Vmpooler
           raise("Pool #{pool_name} does not exist for the provider #{name}") if pool.nil?
 
           vm_hash = nil
+          with_circuit_breaker do
             @connection_pool.with_metrics do |pool_object|
               connection = ensured_vsphere_connection(pool_object)
               # Assume all pool config is valid i.e. not missing
@@ -389,18 +394,23 @@ module Vmpooler
 
               vm_hash = generate_vm_hash(new_vm_object, pool_name)
             end
+          end
           vm_hash
         end
 
         # The inner method requires vmware tools running in the guest os
         def get_vm_ip_address(vm_name, pool_name)
+          ip = nil
+          with_circuit_breaker do
             @connection_pool.with_metrics do |pool_object|
               connection = ensured_vsphere_connection(pool_object)
               vm_object = find_vm(pool_name, vm_name, connection)
               vm_hash = generate_vm_hash(vm_object, pool_name)
-            return vm_hash['ip']
+              ip = vm_hash['ip']
             end
           end
+          ip
+        end
 
         def create_config_spec(vm_name, template_name, extra_config)
           RbVmomi::VIM.VirtualMachineConfigSpec(
@@ -540,11 +550,12 @@ module Vmpooler
         end
 
         def destroy_vm(pool_name, vm_name)
+          with_circuit_breaker do
             @connection_pool.with_metrics do |pool_object|
               connection = ensured_vsphere_connection(pool_object)
               vm_object = find_vm(pool_name, vm_name, connection)
               # If a VM doesn't exist then it is effectively deleted
-            return true if vm_object.nil?
+              next if vm_object.nil?
 
               # Poweroff the VM if it's running
               vm_object.PowerOffVM_Task.wait_for_completion if vm_object.runtime&.powerState && vm_object.runtime.powerState == 'poweredOn'
@@ -552,6 +563,7 @@ module Vmpooler
               # Kill it with fire
               vm_object.Destroy_Task.wait_for_completion
             end
+          end
           true
         end
 
@@ -631,6 +643,14 @@ module Vmpooler
         DISK_TYPE = 'thin'
         DISK_MODE = 'persistent'
 
+        def with_circuit_breaker(&block)
+          if circuit_breaker
+            circuit_breaker.call(&block)
+          else
+            yield
+          end
+        end
+
         def ensured_vsphere_connection(connection_pool_object)
           connection_pool_object[:connection] = connect_to_vsphere unless vsphere_connection_ok?(connection_pool_object[:connection])
           connection_pool_object[:connection]