Fix git branch repos pipeline

  - use `git fetch` instead of `git remote update`
  - use `git branch` instead of `git checkout -b`

Change-Id: Icd40383c456bbf78703f8347832c7c092681be91
See: https://mirantis.jira.com/browse/PROD-24436
diff --git a/branch-git-repos.groovy b/branch-git-repos.groovy
index 0624c40..b5a65b5 100644
--- a/branch-git-repos.groovy
+++ b/branch-git-repos.groovy
@@ -110,14 +110,14 @@
                 sh 'git config user.email "ci+infra@mirantis.com"'
 
                 // Update list of branches
-                sh 'git remote update origin --prune'
+                sh 'git fetch --prune --tags'
 
                 // Ensure there is no branch or tag with gitBranchNew name
                 sh "git branch -d '${gitBranchNew}' && git push origin ':${gitBranchNew}' || :"
                 sh "git tag    -d '${gitBranchNew}' && git push origin ':refs/tags/${gitBranchNew}' || :"
 
                 // Create new branch
-                sh "git checkout -b '${gitBranchNew}' '${gitSrcObj}'" // Create new local branch
+                sh "git branch '${gitBranchNew}' '${gitSrcObj}'"      // Create new local branch
                 sh "git push origin '${gitBranchNew}'"                // ... push new branch
             }
         }