fix regex syntax for blocking multiple jobs from running in bml

Change-Id: Idc53e99d630720569a04eadae088bb6b212ca6e4
diff --git a/jjb/metal3/job_bml_main_integration_tests.yml b/jjb/metal3/job_bml_main_integration_tests.yml
index a246087..039d93c 100644
--- a/jjb/metal3/job_bml_main_integration_tests.yml
+++ b/jjb/metal3/job_bml_main_integration_tests.yml
@@ -84,7 +84,7 @@
     - build-blocker:
         use-build-blocker: true
         blocking-jobs:
-            - ".*_bml_integration_tests_*"
+            - ".*_bml_integration_tests_centos"
         block-level: 'GLOBAL'
 
     triggers: