[release/6.0] Disable SslStress and HttpStress runs (#104714)

* Remove release/6.0 from HttpStress

Follow up from #103572. Seems like the schedule must be disabled in the particular branch (see https://learn.microsoft.com/en-us/azure/devops/pipelines/process/scheduled-triggers?view=azure-devops&tabs=yaml)

* Update ssl.yml

Author: rzikm

eng/pipelines/libraries/stress/http.yml

@@ -11,7 +11,6 @@ schedules:
   branches:
     include:
     - main
-    - release/6.0
 
 variables:
   - template: ../variables.yml

eng/pipelines/libraries/stress/ssl.yml

@@ -11,7 +11,6 @@ schedules:
   branches:
     include:
     - main
-    - release/6.0
 
 variables:
   - template: ../variables.yml