Refactor conditional statement for TARGET_ENV comparison

Changed the conditional statement from using single brackets and == operator to double brackets and = operator for improved compatibility and correctness when comparing values of TARGET_ENV. This change ensures that the comparison works as expected for both "staging" and "production" values.

.gitlab-ci.yml

@@ -51,7 +51,7 @@ build_packer:
     - 'sed -i -E "s/(sacct_log_file_path: ).*/\1\/CRI_Cluster_Monitor\/slurm-cluster.log/" CRI_Cluster_Monitor/group_vars/all'
     - 'sed -i -E "s/(enable_user_reg: ).*/\1false/" CRI_XCBC/group_vars/all'
     - |
-      if [ "$TARGET_ENV" == "staging" || "$TARGET_ENV" == "production" ]; then
+      if [[ "$TARGET_ENV" == "staging" || "$TARGET_ENV" == "production" ]]; then
         'sed -i -E "s/(enable_UAB_UI: ).*/\1true/" CRI_Cluster_Monitor/group_vars/all'
       fi
     - echo $PKR_VAR_s3_endpoint