[fix][slack] send notification even if build `not_built`

current setup failed to send webhook if build status not in:
success,failure or unstable. It breaks messaging if build status:
`not_built`
us: https://mirantis.jira.com/browse/PRODX-3254

Change-Id: Ifabbdcbe7851c16e5ce1cc2b3b125add9e0513f9
diff --git a/src/com/mirantis/mcp/SlackNotification.groovy b/src/com/mirantis/mcp/SlackNotification.groovy
index 6cc73bc..12d6825 100644
--- a/src/com/mirantis/mcp/SlackNotification.groovy
+++ b/src/com/mirantis/mcp/SlackNotification.groovy
@@ -44,15 +44,23 @@
     def common = new com.mirantis.mk.Common()
     cred = common.getCredentialsById(credentialsId)
     hook_url_parsed = cred.getSecret().toString()
-    if (buildStatusParam.toLowerCase().equals("success")) {
-        colorCode = "#00FF00"
-        colorName = "green"
-    } else if (buildStatusParam.toLowerCase().equals("unstable")) {
-        colorCode = "#FFFF00"
-        colorName = "yellow"
-    } else if (buildStatusParam.toLowerCase().equals("failure")) {
-        colorCode = "#FF0000"
-        colorName = "red"
+
+    switch(buildStatusParam.toLowerCase) {
+        case "success":
+            colorCode = "#00FF00"
+            colorName = "green"
+            break
+        case "unstable":
+            colorCode = "#FFFF00"
+            colorName = "yellow"
+            break
+        case "failure":
+            colorCode = "#FF0000"
+            colorName = "red"
+            break
+        default:
+            colorCode = "#808080"
+            colorName = "grey"
     }
 
     queryString = 'payload={' +