Add pmm-admin start --all and pmm-admin stop --all bats tests

[ShahriyarR]

For generic tests there are tests pmm-admin start and pmm-admin stop, also --all command should be added with separate tests

[ShahriyarR]

$ ~/percona-qa/pmm-tests/pmm-framework.sh --addclient=ps,4
User 'admin' is already present in MySQL server. Please create Orchestrator user manually.
[linux:metrics] OK, now monitoring this system.
[mysql:metrics] OK, now monitoring MySQL metrics using DSN root:***@unix(/tmp/PS_NODE_1.sock)
[mysql:queries] OK, now monitoring MySQL queries from perfschema using DSN root:***@unix(/tmp/PS_NODE_1.sock)
User 'admin' is already present in MySQL server. Please create Orchestrator user manually.
[linux:metrics] OK, already monitoring this system.
[mysql:metrics] OK, now monitoring MySQL metrics using DSN root:***@unix(/tmp/PS_NODE_2.sock)
[mysql:queries] OK, now monitoring MySQL queries from perfschema using DSN root:***@unix(/tmp/PS_NODE_2.sock)
User 'admin' is already present in MySQL server. Please create Orchestrator user manually.
[linux:metrics] OK, already monitoring this system.
[mysql:metrics] OK, now monitoring MySQL metrics using DSN root:***@unix(/tmp/PS_NODE_3.sock)
[mysql:queries] OK, now monitoring MySQL queries from perfschema using DSN root:***@unix(/tmp/PS_NODE_3.sock)
Orchestrator username :  admin
Orchestrator password :  passw0rd
[linux:metrics] OK, already monitoring this system.
[mysql:metrics] OK, now monitoring MySQL metrics using DSN root:***@unix(/tmp/PS_NODE_4.sock)
[mysql:queries] OK, now monitoring MySQL queries from perfschema using DSN root:***@unix(/tmp/PS_NODE_4.sock)
[shahriyar.rzaev@qaserver-02 Percona_Servers]$ sudo pmm-admin restart --all
OK, restarted 6 services.

So the service count for our tests is instance count + 2 each time

[ShahriyarR]

I am going to pause implementing this due to:
https://jira.percona.com/browse/PMM-975

[RoelVdP]

@Nailya could you have a look at this ticket + PMM-975 please?

[Nailya]

PMM-975 is still reproducible