Changed examples deleting Elasticsearch indices

[mnocon]

Target: master, 4.6, 3.3

Community feedback:

Hi, can you please update https://doc.ibexa.co/en/latest/update_and_migration/from_4.5/update_from_4.5/#updateelasticsearch-schema  to indicate that the DELETE curl with 'all' is highly destructive and should not be run on elastic.co hosted servers. instead the curl should target the specific CMS indexes like 'default*'

I've verified locally that it works by running the Elasticsearch container and then executing:

php bin/console ibexa:reindex
curl --request DELETE 'http://0.0.0.0:9200/default_content*'
curl --request DELETE 'http://0.0.0.0:9200/default_location*'
php bin/console ibexa:elasticsearch:put-index-template
php bin/console ibexa:reindex

which is enough to solve the issue described in https://issues.ibexa.co/browse/IBX-3758, but potentially less desctuctive.