fix: SearchIndex.replace_all_objects is stuck when using "safe" mode

[r0ro]

Q	A
Bug fix?	yes
New feature?	no
BC breaks?	no
Related Issue	Fix #481
Need Doc update	no

Describe your change

create new SearchIndex instance when creating a temporary index in replace_all_objects

as per doc: https://www.algolia.com/doc/api-reference/api-methods/replace-all-objects/,

when replacing all objects, a temporary index is used to store new data, and once ready it replace the original index.

There was an issue when replace_all_objects was called with 'safe' move:

• when copying the existing index, and only replacing the index name, the name of _search_index (from SearchIndexAsync constructor) was not replaced with the temporary index name (tmp_index_name)
• after that, when tracking the task progress in IndexingResponse.wait the original index name from _search_index was used instead of the tmp_index_name

What problem is this fixing?

Although it was working before, when tracked using the wrong index name, the indexing task is stuck with status notPublished. (maybe it's something that should also be fixed on the backend ?)

With this patch, instead of trying to patch SearchIndex copied instance, we create a new clean instance.

When updating a "dev" index, previous call history would be:

# save_objects calls
--> POST 1/indexes/dev_tmp_aNCOSqmzOQ/batch {'requests': [{'action': 'updateObject', 'body': ... }]}
<-- 200 / {'objectIDs': ['obj_1', ...], 'taskID': 81739652001}

# track task progress in wait call

--> GET 1/indexes/dev/task/81739652001 None
<-- 200 / {'status': 'notPublished', 'pendingTask': False}
--> GET 1/indexes/dev/task/81739652001 None
<-- 200 / {'status': 'notPublished', 'pendingTask': False}

[ ... ] forever

after the fix the task is tracked on the correct index:

# save_objects calls
--> POST 1/indexes/dev_tmp_aNCOSqmzOQ/batch {'requests': [{'action': 'updateObject', 'body': ... }]}
<-- 200 / {'objectIDs': ['obj_1', ...], 'taskID': 81739652001}

# track task progress in wait call

--> GET 1/indexes/dev_tmp_aNCOSqmzOQ/task/81739652001 None
<-- 200 / {'status': 'notPublished', 'pendingTask': False}
--> GET 1/indexes/dev_tmp_aNCOSqmzOQ/task/81739652001 None
<-- 200 / {'status': 'notPublished', 'pendingTask': False}

[ ... ]

--> GET 1/indexes/dev_tmp_aNCOSqmzOQ/task/81739652001 None
<-- 200 / {'status': 'published', 'pendingTask': False}

[r0ro]

alternate fix to #479

[nunomaduro]

Duplicated of: https://github.com/algolia/algoliasearch-client-python/pull/479.