fix: create volume mount with cacert when caCertFile is defined

[pavel-snyk]

This PR fixes an issue when cacert configmap was not created with defined caCertFile value.

Developer notes:

Failing unit tests (and snapshots) after fix show that exactly this envvar and volume was not mounted to the deployment.

	- asserts[0] `matchSnapshot` fail
			Template:	snyk-broker/templates/broker_deployment.yaml
			DocumentIndex:	0
			Path:	
			Expected to match snapshot 1:
				--- Expected
				+++ Actual
				@@ -48,2 +48,6 @@
				               value: "false"
				+            - name: CA_CERT
				+              value: /home/node/cacert/cacert
				+            - name: NODE_EXTRA_CA_CERTS
				+              value: /home/node/cacert/cacert
				             - name: ACCEPT_CODE
				@@ -93,6 +97,12 @@
				             runAsUser: 1000
				-          volumeMounts: null
				+          volumeMounts:
				+            - mountPath: /home/node/cacert
				+              name: RELEASE-NAME-snyk-broker-cacert-volume
				+              readOnly: true
				       securityContext: {}
				       serviceAccountName: snyk-broker
				-      volumes: null
				+      volumes:
				+        - configMap:
				+            name: RELEASE-NAME-snyk-broker-cacert-configmap
				+          name: RELEASE-NAME-snyk-broker-cacert-volume