chore: Migrate gsutil usage to gcloud storage (#10216)

Author: gurusai-voleti

bigtable/beam/change-streams/README.md

@@ -139,7 +139,7 @@ Google Cloud Storage.
 1. Observe the output on GCS and see the most popular songs.
 
     ```sh
-    gsutil cat ${OUTPUT_LOCATION}/song-charts/GlobalWindow-pane-0-00000-of-00001.txt 
+    gcloud storage cat ${OUTPUT_LOCATION}/song-charts/GlobalWindow-pane-0-00000-of-00001.txt 
     ```
 
    Example output:

bigtable/spark/README.md

@@ -317,23 +317,23 @@ One notable change (compared to the earlier executions) is that the example uses
 1. Create a bucket.
 
 ```
-gsutil mb \
-  -b on \
-  -l $BIGTABLE_SPARK_DATAPROC_REGION \
-  -p $BIGTABLE_SPARK_PROJECT_ID \
+gcloud storage buckets create \
+  --uniform-bucket-level-access \
+  --location=$BIGTABLE_SPARK_DATAPROC_REGION \
+  --project=$BIGTABLE_SPARK_PROJECT_ID \
   $BIGTABLE_SPARK_BUCKET_NAME
 ```
 
 1. Upload an input file into the bucket.
 
 ```
-gsutil cp src/test/resources/Romeo-and-Juliet-prologue.txt $BIGTABLE_SPARK_BUCKET_NAME
+gcloud storage cp src/test/resources/Romeo-and-Juliet-prologue.txt $BIGTABLE_SPARK_BUCKET_NAME
 ```
 
 1. List contents of the bucket.
 
 ```
-gsutil ls $BIGTABLE_SPARK_BUCKET_NAME
+gcloud storage ls $BIGTABLE_SPARK_BUCKET_NAME
 ```
 
 Output should be:
@@ -413,6 +413,6 @@ gcloud dataproc clusters list \
 Remove the input file in the bucket and the bucket itself.
 
 ```
-gsutil rm $BIGTABLE_SPARK_BUCKET_NAME/Romeo-and-Juliet-prologue.txt
-gsutil rb $BIGTABLE_SPARK_BUCKET_NAME
+gcloud storage rm $BIGTABLE_SPARK_BUCKET_NAME/Romeo-and-Juliet-prologue.txt
+gcloud storage buckets delete $BIGTABLE_SPARK_BUCKET_NAME
 ```