Standard token filter can still appear in indices created in 7x #62644
Description
Indices that try to use a standard token filter in 7x are supposed to fail. However this detection was broken in previous versions of Elasticsearch (from 7.0 to 7.5) due to a bug, so some indices in 7x may still declare a standard token version that when upgraded to a version with the fix (>=7.6.0) causes issues in the cluster (the index fails to open). I am opening this issue to discuss the possible solutions to fix this discrepancy automatically for users. One solution for instance could be to ignore all standard token filter if they are on an index created before the last fix.