Switch to new trySlackSend named colors

Signed-off-by: Geoff Levand <geoff@infradead.org>

os/board/sign-image.groovy

@@ -106,7 +106,7 @@ stage('Wait') {
     def msg = """The ${params.BOARD} ${version ?: "UNKNOWN"} build is waiting for the boot loader files to be signed for Secure Boot and uploaded to continue.\n
 When all boot loader files are uploaded, go to ${BUILD_URL}input and proceed with the build."""
 
-    trySlackSend color: '#C0C0C0', message: msg
+    trySlackSend color: 'grey', message: msg
     input 'Waiting for the signed UEFI binaries to be ready...'
 }
 

os/docs-sync.groovy

@@ -176,7 +176,7 @@ git -C coreos-pages push -f ${forkUrl} ${branch}
                                         sourceBranch: branch,
                                         title: "os: sync ${version}",
                                         message: "From: ${env.BUILD_URL}"
-            trySlackSend color: '#2020C0',
+            trySlackSend color: 'persian',
                       message: "${version} (${channel}) docs: ${url}"
         }
     }

os/glsa.groovy

@@ -106,7 +106,7 @@ exit 0  # Do not return a non-zero $? from above.
         def color = readFile 'status.txt'
         def message = readFile 'notify.txt'
         if (message)
-            trySlackSend color: color ?: '#C0C0C0', message: """${message}
+            trySlackSend color: color ?: 'grey', message: """${message}
 Run `update_ebuilds --commit --portage=rsync metadata/glsa` in the SDK to \
 update GLSA definitions."""
     }

os/manifest.groovy

@@ -287,7 +287,7 @@ do
 done
 '''  /* Editor quote safety: ' */
             }
-            trySlackSend color: '#2020C0', message: readFile('message.txt').trim()
+            trySlackSend color: 'persian', message: readFile('message.txt').trim()
         }
     }
 }