Use common ci 1x 8x (#195)

* Update the LOGSTASH_PATH of gralde.properties.

* Use common .ci -> 1.x as we are doing with rest of plugins.

Author: mashhurs

.buildkite/scripts/run_tests.sh

@@ -12,4 +12,4 @@ else
   git checkout "$TARGET_BRANCH"
 fi
 
-mkdir -p .ci && curl -sL --retry 5 --retry-delay 5 https://github.com/logstash-plugins/.ci/archive/buildkite-1.x.tar.gz | tar zxvf - --skip-old-files --strip-components=1 -C .ci --wildcards '*Dockerfile*' '*docker*' '*.sh' && .ci/docker-setup.sh && .ci/docker-run.sh
+mkdir -p .ci && curl -sL --retry 5 --retry-delay 5 https://github.com/logstash-plugins/.ci/archive/1.x.tar.gz | tar zxvf - --skip-old-files --strip-components=1 -C .ci --wildcards '*Dockerfile*' '*docker*' '*.sh' && .ci/docker-setup.sh && .ci/docker-run.sh

.ci/docker-run.sh

@@ -1,2 +1,2 @@
-LOGSTASH_PATH=../../ls
+LOGSTASH_PATH=../../logstash
 ELASTICSEARCH_TREEISH=8.16