Merge branch 'update-ee-downgrade-instructions' into 'master'

Update EE downgrade instructions to include JenkinsDeprecatedService

EE now includes JenkinsDeprecatedService in addition to JenkinsService, so we need to clean both when downgrading from EE to CE.

Closes #19133
    
[ci skip]

See merge request !4916

doc/downgrade_ee_to_ce/README.md

@@ -44,13 +44,13 @@ to avoid getting this error, you need to remove all instances of the
 **Omnibus Installation**
 
 ```
-$ sudo gitlab-rails runner "Service.where(type: 'JenkinsService').delete_all"
+$ sudo gitlab-rails runner "Service.where(type: ['JenkinsService', 'JenkinsDeprecatedService']).delete_all"
 ```
 
 **Source Installation**
 
 ```
-$ bundle exec rails runner "Service.where(type: 'JenkinsService').delete_all" production
+$ bundle exec rails runner "Service.where(type: ['JenkinsService', 'JenkinsDeprecatedService']).delete_all" production
 ```
 
 ## Downgrade to CE