Do not download checks and templates from Portal if telemetry is disabled

STR:

1. Install PMM
2. Go to settings and Disable Telemetry toggle + Enable  STT and  Integrated Alerting. 
3. Save  settings 
4. Go to STT and Alerting menu  - Alert Templates 

Expected results: 

• No STT  checks 
• Do not have alerts where the source  = Percona.com  (1 alert for now)

Given results: 

• all set of checks 
• all alert Templates, including the percona.com source  

User impact:

With disabled telemetry, PMM still executes calls to Percona.com, which might lead to extracting the information about the instance. This might affect people who sensitive to the telemetry data