Stop freezing elasticsearch indexes.

Elasticsearch 7.14 has deprecated index freezing, thanks to improvements in heap memory usage[1]. So we can stop freezing indexes and just close them, which should also reduce issues with logstash on restarting servers.

• [1] https://www.elastic.co/blog/significantly-decrease-your-elasticsearch-heap-memory-usage

Test Plan

checked that the updated script works on a local elasticsearch

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Migrated from D6655 (view on Phabricator)