chore(pingcap/tidb): update trigger for CI job `pull-br-integration-t…

…est` (#3040)

Also trigger`BR` integration testing when changes are made to `DDL`
module. @BornChanger @Benjamin2037

Fixes #3039

Signed-off-by: wuhuizuo <wuhuizuo@126.com>

---------

Signed-off-by: wuhuizuo <wuhuizuo@126.com>

prow-jobs/pingcap/tidb/latest-presubmits.yaml

@@ -102,7 +102,7 @@ presubmits:
       agent: jenkins
       decorate: false # need add this.
       context: pull-br-integration-test
-      run_if_changed: "br/.*"
+      run_if_changed: "(br|pkg/ddl|pkg/domain)/.*"
       optional: false
       skip_report: false
       trigger: "(?m)^/test (?:.*? )?pull-br-integration-test(?: .*?)?$"