[BUG] Auto-complete menu of Dev Tools is missing _index_template and perhaps others

[AMoo-Miki]

Just like _cat, _template and many others appear when keying in, _index_template should appear in the list as well.

To Reproduce
Steps to reproduce the behavior:

1. Go to Dev Tools
2. Key in _template
3. Notice that _index_template isn't in the auto-complete list

Expected behavior
_index_template in the list

OpenSearch Version
1.3

Dashboards Version
1.3

Additional context

It is possible that other specs are missing as well.

[kristenTian]

https://cptnb.github.io/opensearch-dashboards-dev-docs/source/readmes/packages/osd-spec-to-console/
https://cptnb.github.io/opensearch-dashboards-dev-docs/source/readmes/src/plugins/data/#autocomplete
https://cptnb.github.io/opensearch-dashboards-dev-docs/core-plugins/console/console/

yarn spec_to_console
yarn run v1.22.19
$ node scripts/spec_to_console
Expected input
error Command failed with exit code 1.

Check if we missing sth spec folder in opensearch.

[joshuarrrr]

Resolved via #2226