[CLONE] [MAGMA] Need StorageBackend Info in terseBucket endpoint

To Enable OSO indexer needs to know the StorageBackend type as OSO should be disabled for Magma Buckets.

In past few changes to optimise interaction with ns_server we have moving away from buckets endpoint and started using terseBucket endpoint. In the cinfo lite that was introduced few months back in GSI and partial fetch of cinfo we use buckets data from terseBucket endpoint.

We will need "storageBackend" field in the output of terseBucket endpoint.

================== CLONED FROM INDEXER BUG ======================

When building index on 5% KV RR, indexes are getting errored out.

Steps to reproduce:

1. Create a single node cluster with KV:N1QL:INDEX services
2. Create a collection and load data to have 5% RR on MAGMA Bucket
3. Create 5 equivalent indexes with defer build

   2022-03-22 23:40:22 | INFO | MainProcess | test_thread | [tuq_helper.run_cbq_query] RUN QUERY CREATE INDEX `idx_0` ON default:test_bucket.test_scope_1.test_collection_1(age) USING GSI WITH {'defer_build': True}

   2022-03-22 23:40:22 | INFO | MainProcess | test_thread | [rest_client.query_tool] query params : statement=CREATE+INDEX+%60idx_0%60+ON+default%3Atest_bucket.test_scope_1.test_collection_1%28age%29+USING+GSI++WITH+%7B%27defer_build%27%3A+True%7D

   2022-03-22 23:40:24 | INFO | MainProcess | test_thread | [tuq_helper.run_cbq_query] TOTAL ELAPSED TIME: 1.731203413s

   2022-03-22 23:40:24 | INFO | MainProcess | test_thread | [tuq_helper.run_cbq_query] RUN QUERY CREATE INDEX `idx_1` ON default:test_bucket.test_scope_1.test_collection_1(age) USING GSI WITH {'defer_build': True}

   2022-03-22 23:40:24 | INFO | MainProcess | test_thread | [rest_client.query_tool] query params : statement=CREATE+INDEX+%60idx_1%60+ON+default%3Atest_bucket.test_scope_1.test_collection_1%28age%29+USING+GSI++WITH+%7B%27defer_build%27%3A+True%7D

   2022-03-22 23:40:25 | INFO | MainProcess | test_thread | [tuq_helper.run_cbq_query] TOTAL ELAPSED TIME: 1.815875677s

   2022-03-22 23:40:25 | INFO | MainProcess | test_thread | [tuq_helper.run_cbq_query] RUN QUERY CREATE INDEX `idx_2` ON default:test_bucket.test_scope_1.test_collection_1(age) USING GSI WITH {'defer_build': True}

   2022-03-22 23:40:25 | INFO | MainProcess | test_thread | [rest_client.query_tool] query params : statement=CREATE+INDEX+%60idx_2%60+ON+default%3Atest_bucket.test_scope_1.test_collection_1%28age%29+USING+GSI++WITH+%7B%27defer_build%27%3A+True%7D

   2022-03-22 23:40:27 | INFO | MainProcess | test_thread | [tuq_helper.run_cbq_query] TOTAL ELAPSED TIME: 1.958516768s

   2022-03-22 23:40:27 | INFO | MainProcess | test_thread | [tuq_helper.run_cbq_query] RUN QUERY CREATE INDEX `idx_3` ON default:test_bucket.test_scope_1.test_collection_1(age) USING GSI WITH {'defer_build': True}

   2022-03-22 23:40:27 | INFO | MainProcess | test_thread | [rest_client.query_tool] query params : statement=CREATE+INDEX+%60idx_3%60+ON+default%3Atest_bucket.test_scope_1.test_collection_1%28age%29+USING+GSI++WITH+%7B%27defer_build%27%3A+True%7D

   2022-03-22 23:40:29 | INFO | MainProcess | test_thread | [tuq_helper.run_cbq_query] TOTAL ELAPSED TIME: 1.202450683s

   2022-03-22 23:40:29 | INFO | MainProcess | test_thread | [tuq_helper.run_cbq_query] RUN QUERY CREATE INDEX `idx_4` ON default:test_bucket.test_scope_1.test_collection_1(age) USING GSI WITH {'defer_build': True}

1.  Run Build indexes query for 2 out of 5 indexes and then run build index query for all indexes
2. Check in the UI, Build for 3 indexes are errored out while initial build for 2 indexes continue to make progress.

Logs are available at - s3://cb-customers-secure/magma_index_error/2022-03-23/collectinfo-2022-03-23t070108-ns_1@172.23.100.38.zip