Get pprof data from server component

Use case: 

pmm-admin summary --pprof should contain pprof data from server

Acceptance criteria:

• summary should contain pprof data from server
• pmm-admin should be run on pmm-server

UI/UX:

$ pmm-admin summary --pprof 

How to test:
1. Login on PMM-SERVER
2. Run 

$ pmm-admin summary --pprof

3. Verify result file

Out of scope:
Gathering server's pprof data outside pmm-server will be delivered in  PMM-5492