ci: allow cherry-picking a manual backport to other release branches

If an automatic backport fails to more than one release branch we need
to crate a PR to backport it. So far we've had to create a backport PR
for each target release branch.

With this change, we may be able to create only a single PR, and then
run the backport automation to cherry-pick it into other release
branches.

The idea is that if a change introduced in version n-1 caused a
conflict, and there are no other changes, then the backport automation
should be able to use the same commit for version n-2 and n-3.

.circleci/config.yml

@@ -1000,3 +1000,4 @@ workflows:
             branches:
               only:
                 - master
+                - /release\/\d+\.\d+\.x$/

.circleci/scripts/cherry-picker.sh

@@ -157,11 +157,12 @@ if echo "$resp" | jq -e '.items[].labels[] | select(.name | contains("docs-cherr
     fi
 fi
 
+git config --local user.email "github-team-consul-core@hashicorp.com"
+git config --local user.name "hc-github-team-consul-core"
+
 backport_failures=0
 # loop through all labels on the PR
 for label in $labels; do
-    git config --local user.email "github-team-consul-core@hashicorp.com"
-    git config --local user.name "hc-github-team-consul-core"
     status "checking label: $label"
     # if the label matches docs-cherrypick, it will attempt to cherry-pick to stable-website
     if [[ $label =~ docs-cherrypick ]]; then