CI: run all gradle commands in one go

right now `./gradlew build` could fail but the script would still go on
(because neither `set -e` is set nor `&&` is used to run both commands
together).

the easiest solution is to just run both gradle target in one go as one
anyway depends on the other - there's no need to start gradle twice.
this will also make the runs ever so slightly faster.

fixes opensearch-project#60

Signed-off-by: Ralph Ursprung <[email protected]>

.github/workflows/CI.yml

@@ -32,6 +32,4 @@ jobs:
 
     - name: Build and Run Tests
       run: |
-          ./gradlew build
-           # Generated by 'opensearch.pluginzip' custom gradle plugin
-          ./gradlew publishPluginZipPublicationToZipStagingRepository
+          ./gradlew build publishPluginZipPublicationToZipStagingRepository