Default enable FF `include_manual_to_pipeline_completion`

What does this MR do and why?

• Default enable the FF.
• Change the FF type from gitlab_com_derisk to beta as we want to have the flexibility to rollback and have not got feedback yet from on-premise customers. gitlab_com_derisk does not support default enabling and beta type is ideal for this scenario.
• Include documentation for this feature enhancement.

Originally introduced in !143046 (merged)

MR acceptance checklist

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Related to #440652 (closed)

doc/user/application_security/vulnerability_report/index.md

@@ -52,7 +52,7 @@ this page displays the vulnerabilities that originate from the selected project.
 
 > - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/439691) in GitLab 16.10 [with a flag](../../../administration/feature_flags.md) named `include_manual_to_pipeline_completion`. Enabled by default.
 
-Previously we were only ingesting security reports after all the jobs in the pipeline is complete. With this feature, we are extending support to ingest reports when the pipeline is [blocked by manual jobs](../../../ci/jobs/job_control.md#types-of-manual-jobs) as well.
+Previously GitLab only supported ingesting security reports after all the jobs in the pipeline is complete. With this feature, we are extending support to ingest reports when the pipeline is [blocked by manual jobs](../../../ci/jobs/job_control.md#types-of-manual-jobs) as well.
 
 ## View the vulnerability report