PMM-14717 Fix missing find action on system.profile in MongoDB monitoring role

[catalinaadam]

Summary

• Adds the missing find action to the system.profile collection resource in the pmmMonitor role definition
• Without find on system.profile, QAN shows no data even when profiling is enabled
• Fix applied in both mongodb.md (connect database guide) and quickstart.md

Changes

Before:

{
  "resource": { "db": "", "collection": "system.profile" },
  "actions": [ "dbStats", "collStats", "indexStats" ]
}

After:

{
  "resource": { "db": "", "collection": "system.profile" },
  "actions": [ "find", "dbStats", "collStats", "indexStats" ]
}

Files changed

• documentation/docs/install-pmm/install-pmm-client/connect-database/mongodb.md
• documentation/docs/quickstart/quickstart.md

Test plan

• Verify the createRole command in mongodb.md includes find on system.profile
• Verify the createRole command in quickstart.md includes find on system.profile
• Confirm QAN populates correctly after applying the updated role on a MongoDB instance

Fixes: PMM-14717