Indices API: Fixed backward compatibility issue

If a 1.4 node needs to forward a GET index API call to a <1.4 master it cannot use the GET index API endpoints as the master has no knowledge of it. This change detects that the master does not understand the initial request and instead tries it again using the old APIs. If these calls also do not work, an error is returned

Closes #8364
FYI if you want (not that it is a problem as it works now) you can leave the randomized number of shards when creating the index and retrieve it through `getNumShards("test").numShards` which you can use for the comparison.