Update Jenkins for 7.12 (#5341)

Author: stevejgordon

.ci/jobs/elastic+elasticsearch-net+7.11.yml

@@ -1,13 +1,13 @@
 ---
 - job:
-    name: elastic+elasticsearch-net+7.10
-    display-name: 'elastic / elasticsearch-net # 7.10'
-    description: Testing the elasticsearch-net 7.10 branch.
+    name: elastic+elasticsearch-net+7.12
+    display-name: 'elastic / elasticsearch-net # 7.12'
+    description: Testing the elasticsearch-net 7.12 branch.
     junit_results: "*-junit.xml"
     parameters:
       - string:
           name: branch_specifier
-          default: refs/heads/7.10
+          default: refs/heads/7.12
           description: The Git branch specifier to build
     triggers:
       - github