HBASE-22924 GitHUB PR job should use when clause to filter to just PRs (#4915)

Signed-off-by: Duo Zhang <zhangduo@apache.org>

Author: shankybnl

dev-support/Jenkinsfile_GitHub

@@ -92,6 +92,10 @@ pipeline {
                         YETUS_DRIVER = "${WORKDIR}/${YETUS_DRIVER_REL}"
                         ASF_NIGHTLIES_GENERAL_CHECK_BASE="${ASF_NIGHTLIES_BASE}/${WORKDIR_REL}/${PATCH_REL}"
                     }
+                    when {
+                        // this will return true if the pipeline is building a change request, such as a GitHub pull request.
+                        changeRequest()
+                    }
                     steps {
                         dir("${SOURCEDIR}") {
                             checkout scm
@@ -215,6 +219,10 @@ pipeline {
                         YETUS_DRIVER = "${WORKDIR}/${YETUS_DRIVER_REL}"
                         SKIP_ERRORPRONE = true
                     }
+                    when {
+                        // this will return true if the pipeline is building a change request, such as a GitHub pull request.
+                        changeRequest()
+                    }
                     steps {
                         dir("${SOURCEDIR}") {
                             checkout scm
@@ -347,6 +355,10 @@ pipeline {
                         YETUS_DRIVER = "${WORKDIR}/${YETUS_DRIVER_REL}"
                         SKIP_ERRORPRONE = true
                     }
+                    when {
+                        // this will return true if the pipeline is building a change request, such as a GitHub pull request.
+                        changeRequest()
+                    }
                     steps {
                         dir("${SOURCEDIR}") {
                             checkout scm

dev-support/jenkins_precommit_github_yetus.sh

@@ -67,14 +67,6 @@ mkdir -p "${PATCHDIR}"
 mkdir "${PATCHDIR}/machine"
 "${SOURCEDIR}/dev-support/gather_machine_environment.sh" "${PATCHDIR}/machine"
 
-# If CHANGE_URL is set (e.g., Github Branch Source plugin), process it.
-# Otherwise exit, because we don't want HBase to do a
-# full build.  We wouldn't normally do this check for smaller
-# projects. :)
-if [[ -z "${CHANGE_URL}" ]]; then
-  echo "Full build skipped" > "${PATCHDIR}/report.html"
-  exit 0
-fi
 # enable debug output for yetus
 if [[ "true" = "${DEBUG}" ]]; then
   YETUS_ARGS+=("--debug")