chore: Service Account Naming Consistency (#11557)

# Which Problems Are Solved

Inconsistent naming of service account, found in the following
variations:

  - Machine User
  - machine user
  - Service User
  - Machine Account
  - Technical Account
  - User: Type Machine

# How the Problems Are Solved

Attentive search and replace.

Localizations have been translated using Copilot

# Additional Changes

Some unused methods have been removed from the Go code.

# Additional Context

- Closes #11285

cmd/setup/53/02-permitted_orgs_function.sql

@@ -38,7 +38,7 @@ BEGIN
         RETURN;
     END IF;
   
-    -- if human/machine user
+    -- if human/service account
     DECLARE
     	matched_roles TEXT[] := eventstore.find_roles(req_instance_id, perm);
 	BEGIN

cmd/setup/53/03-permitted_projects_func.sql

@@ -29,7 +29,7 @@ BEGIN
         RETURN;
     END IF;
 
-    -- if human/machine user
+    -- if human/service account
     SELECT * FROM eventstore.permitted_orgs(
         req_instance_id
         , auth_user_id

cmd/setup/steps.yaml

@@ -122,7 +122,7 @@ FirstInstance:
   Org:
     Name: ZITADEL # ZITADEL_FIRSTINSTANCE_ORG_NAME
     # In the FirstInstance.Org.Human section, the initial organization's admin user with the role IAM_OWNER is defined.
-    # If FirstInstance.Org.Machine.Machine is defined, a service user is created with the IAM_OWNER role.
+    # If FirstInstance.Org.Machine.Machine is defined, a service account is created with the IAM_OWNER role.
     Human:
       # In case UserLoginMustBeDomain is false (default) and you don't overwrite the username with an email,
       # it will be suffixed by the org domain (org-name + domain from config).
@@ -144,7 +144,7 @@ FirstInstance:
       Password: Password1! # ZITADEL_FIRSTINSTANCE_ORG_HUMAN_PASSWORD
       PasswordChangeRequired: true # ZITADEL_FIRSTINSTANCE_ORG_HUMAN_PASSWORDCHANGEREQUIRED
     # In the FirstInstance.Org.Machine section, the initial organization's admin user with the role IAM_OWNER is defined.
-    # If FirstInstance.Org.Machine.Machine is defined, a service user is created with the IAM_OWNER role.
+    # If FirstInstance.Org.Machine.Machine is defined, a service account is created with the IAM_OWNER role.
     Machine:
       Machine:
         Username: # ZITADEL_FIRSTINSTANCE_ORG_MACHINE_MACHINE_USERNAME