Disable PR merge job

it runs on production now

Signed-off-by: Arthur She <arthur.she@linaro.org>
Change-Id: I4979d0241d0df541d47401ce579cb588cc61fa61
diff --git a/mbed-tls-pr-merge.yaml b/mbed-tls-pr-merge.yaml
index 1af1d8c..84c8fea 100644
--- a/mbed-tls-pr-merge.yaml
+++ b/mbed-tls-pr-merge.yaml
@@ -1,7 +1,7 @@
 - job:
     name: mbed-tls-pr-merge
     description: 'Job for testing PRs merged with the target branch head'
-    disabled: false
+    disabled: true
     project-type: multibranch
     prune-dead-branches: true
     days-to-keep: 60