Improve Advanced Search counts queries

What does this MR do?

This MR changes ES queries that we use for counts (e.g. /search/count?group_id=&project_id=&repository_ref=&scope=blobs&search=update) to make them more performant.

• Move the Clause from MUST to FILTER this will save the "score" calculation.
• Remove Boosting for simple_query_string fields. This will also prevent calculation scores.
• Set the Size 0 , This will prevent fetching the documents.

#299099 (closed)

Query benchmark with hyperfine

This is a simple benchmark comparing old and new issues query

❯ hyperfine './old.sh' './new.sh'
Benchmark #1: ./old.sh
  Time (mean ± σ):      17.0 ms ±   1.8 ms    [User: 5.1 ms, System: 2.4 ms]
  Range (min … max):    12.9 ms …  24.1 ms    122 runs

Benchmark #2: ./new.sh
  Time (mean ± σ):      10.0 ms ±   1.0 ms    [User: 5.1 ms, System: 2.3 ms]
  Range (min … max):     6.8 ms …  13.7 ms    251 runs

Summary
  './new.sh' ran
    1.70 ± 0.24 times faster than './old.sh'

scripts

❯ cat old.sh
#!/bin/sh

curl -XPOST -s -H "Content-Type: application/json" http://localhost:9200/gitlab-development-issues/_search --data-binary "@old.json" > /dev/null
❯ cat old.json
{"query":{"bool":{"must":[{"simple_query_string":{"_name":"issue:match:search_terms","fields":["iid^3","title^2","description"],"query":"update","lenient":true,"default_operator":"and"}}],"filter":[{"term":{"type":{"_name":"doc:is_a:issue","value":"issue"}}},{"bool":{"should":[{"bool":{"filter":[{"term":{"visibility_level":{"_name":"issue:authorized:project:any","value":0}}},{"terms":{"_name":"issue:authorized:project:issues:enabled_or_private","issues_access_level":[20,10]}}]}},{"bool":{"_name":"issue:authorized:project:visibility:10:issues:access_level","filter":[{"term":{"visibility_level":{"_name":"issue:authorized:project:visibility:10","value":10}}},{"terms":{"_name":"issue:authorized:project:visibility:10:issues:access_level:enabled_or_private","issues_access_level":[20,10]}}]}},{"bool":{"_name":"issue:authorized:project:visibility:20:issues:access_level","filter":[{"term":{"visibility_level":{"_name":"issue:authorized:project:visibility:20","value":20}}},{"terms":{"_name":"issue:authorized:project:visibility:20:issues:access_level:enabled_or_private","issues_access_level":[20,10]}}]}}]}}]}},"highlight":{"fields":{"iid":{},"title":{},"description":{}},"number_of_fragments":0,"pre_tags":["gitlabelasticsearch→"],"post_tags":["←gitlabelasticsearch"]}}
❯ cat new.sh
#!/bin/sh

curl -XPOST -s -H "Content-Type: application/json" http://localhost:9200/gitlab-development-issues/_search --data-binary "@new.json" > /dev/null
❯ cat new.json
{"query":{"bool":{"filter":[{"term":{"type":{"_name":"doc:is_a:issue","value":"issue"}}},{"simple_query_string":{"_name":"issue:match:search_terms","fields":["iid","title","description"],"query":"update","lenient":true,"default_operator":"and"}},{"bool":{"should":[{"bool":{"filter":[{"term":{"visibility_level":{"_name":"issue:authorized:project:any","value":0}}},{"terms":{"_name":"issue:authorized:project:issues:enabled_or_private","issues_access_level":[20,10]}}]}},{"bool":{"_name":"issue:authorized:project:visibility:10:issues:access_level","filter":[{"term":{"visibility_level":{"_name":"issue:authorized:project:visibility:10","value":10}}},{"terms":{"_name":"issue:authorized:project:visibility:10:issues:access_level:enabled_or_private","issues_access_level":[20,10]}}]}},{"bool":{"_name":"issue:authorized:project:visibility:20:issues:access_level","filter":[{"term":{"visibility_level":{"_name":"issue:authorized:project:visibility:20","value":20}}},{"terms":{"_name":"issue:authorized:project:visibility:20:issues:access_level:enabled_or_private","issues_access_level":[20,10]}}]}}]}}]}},"size":0}

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #299099 (closed)