Draft: Use direct SQL to generate internal ids

What does this MR do?

Related issue: #325861 (closed)

Finish up implementation from !57412 (closed) that removes database round-trips and explicit locking when updating internal_ids. We make the assumption on generating a new value that most operations will modify existing records, so we prefer to attempt to update the row first.

Example of creation of object with internal_id, where no existing record exists (create_record!):

  Update InternalId (0.7ms)  UPDATE "internal_ids" SET "last_value" = ("internal_ids"."last_value" + 1) WHERE "internal_ids"."project_id" = 7 AND "internal_ids"."usage" = 0 RETURNING "last_value" /*application:console,line:/app/models/internal_id.rb:91:in `update_record!'*/
  TRANSACTION (0.1ms)  SAVEPOINT active_record_1 /*application:console,line:/app/models/concerns/atomic_internal_id.rb:211:in `block in project_init'*/
   (2.1ms)  SELECT MAX("issues"."iid") FROM "issues" WHERE "issues"."project_id" = 7 /*application:console,line:/app/models/concerns/atomic_internal_id.rb:211:in `block in project_init'*/
  InternalId Create (0.7ms)  INSERT INTO "internal_ids" ("project_id", "usage", "last_value") VALUES (7, 0, 1) RETURNING "id" /*application:console,line:/app/models/internal_id.rb:102:in `block in create_record!'*/

First attempts to update the existing record, and because none is found, it creates a new record. If the new record were to conflict with a concurrent insert, it retries the update.

Example of update of object with internal_id, where a record exists (update_record!):

 Update InternalId (0.3ms)  UPDATE "internal_ids" SET "last_value" = ("internal_ids"."last_value" + 1) WHERE "internal_ids"."project_id" = 7 AND "internal_ids"."usage" = 0 RETURNING "last_value" /*application:console,line:/app/models/internal_id.rb:91:in `update_record!'*/

It updates the record only.

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.
• I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.

Security

Does this MR contain changes to processing or storing of credentials or tokens, authorization and authentication methods or other items described in the security review guidelines? If not, then delete this Security section.

• 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