Add dedicated endpoints for project VSA

What does this MR do?

Introduces dedicated endpoints for fetching project value stream data, these endpoints were added in !66439 (merged) so we can now replace the existing project cycle analytics endpoints.

This MR:

• Adds the new api requests for medians, records and stage counts to ~/api/analytics_api.js
• Replaces the project VSA requests for records (stage events)
• Replaces the project VSA stage median requests

Note: stage counts will be introduced in a follow-up MR

Screenshots or Screencasts (strongly suggested)

For verification, the data remains the same

Before	After

How to setup and validate locally (strongly suggested)

1. Seed VSA data for a project

$ VSA_SEED_PROJECT_ID=<project-id> VSA_ISSUE_COUNT=10 SEED_VSA=true FILTER=cycle_analytics rake db:seed_fu

1. Visit value stream analytics for any project, for example http://gdk.test:3001/vsa-life/ror-project-vsa/-/value_stream_analytics
2. The page should load with any available data, changing the date range or click on on a stage should refetch the data

Note: if the project does not belong to a group, you might need to apply this patch to run the seeding script, this should be fixed with !67222 (merged)

diff --git a/db/fixtures/development/17_cycle_analytics.rb b/db/fixtures/development/17_cycle_analytics.rb
index 826e703a443..a034c25f47a 100644
--- a/db/fixtures/development/17_cycle_analytics.rb
+++ b/db/fixtures/development/17_cycle_analytics.rb
@@ -149,7 +149,7 @@ def create_developers!
         email: "vsm-user-#{i}@#{suffix}.com"
       )
-      project.group.add_developer(user)
+      project.group.add_developer(user) if project&.group
       project.add_developer(user)
       @developers << user

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

Related to #335953 (closed)