chore: fix duplicated java java (#10939)

* chore: revert duplicated java-java in config yaml

* update input message

Author: diegomarquezp

.github/workflows/generate_new_client_hermetic_build.yaml

@@ -41,7 +41,7 @@ on:
           type: string
           description: |
             `library_name`: The directory name of the new library. By default it's
-            java-<api_shortname>
+            java-<api_shortname>. **Do not include `java-` as it will be automatically prepended**
         distribution_name:
           required: false
           type: string

generation_config.yaml

@@ -1139,7 +1139,7 @@ libraries:
   cloud_api: false
   GAPICs:
   - proto_path: google/shopping/merchant/products/v1beta
-  library_name: java-shopping-merchant-products
+  library_name: shopping-merchant-products
 - api_shortname: merchantapi
   name_pretty: Merchant API
   product_documentation: https://developers.google.com/merchant/api
@@ -1154,7 +1154,7 @@ libraries:
   cloud_api: false
   GAPICs:
   - proto_path: google/shopping/merchant/datasources/v1beta
-  library_name: java-shopping-merchant-datasources
+  library_name: shopping-merchant-datasources
   requires_billing: true
 - api_shortname: merchantapi
   name_pretty: Merchant API
@@ -1170,7 +1170,7 @@ libraries:
   cloud_api: false
   GAPICs:
   - proto_path: google/shopping/merchant/accounts/v1beta
-  library_name: java-shopping-merchant-accounts
+  library_name: shopping-merchant-accounts
   requires_billing: true
 - api_shortname: merchantapi
   name_pretty: Merchant API
@@ -1186,7 +1186,7 @@ libraries:
   cloud_api: false
   GAPICs:
   - proto_path: google/shopping/merchant/promotions/v1beta
-  library_name: java-shopping-merchant-promotions
+  library_name: shopping-merchant-promotions
   requires_billing: true
 - api_shortname: cloudkms
   name_pretty: Cloud Key Management Service