Skip startup library for primo mode (#43019)

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**Related issue:** Resolves #40791

# Checklist for submitter

If some of the following don't apply, delete the relevant line.

- [ ] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.
See [Changes
files](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/guides/committing-changes.md#changes-files)
for more information.

## Testing

- [ ] Added/updated automated tests
We don't typically do new primo mode tests. As long as existing tests
for startup library pass, we're good.
- [X] QA'd all new/changed functionality manually
- [X] tested that starting a new instance with
`FLEET_PARTNERSHIPS_ENABLE_PRIMO=true` causes the starter library not to
be applied (no fleets, labels or policies

server/config/config.go

@@ -1622,7 +1622,7 @@ func (man Manager) addConfigs() {
 	man.addConfigString("microsoft_compliance_partner.proxy_api_key", "", "Shared key required to use the Microsoft Compliance Partner proxy API")
 	man.addConfigString("microsoft_compliance_partner.proxy_uri", "https://fleetdm.com", "URI of the Microsoft Compliance Partner proxy (for development/testing)")
 
-	man.addConfigBool("partnerships.enable_primo", false, "Cosmetically disables team capabilities in the UI")
+	man.addConfigBool("partnerships.enable_primo", false, "Disables the ability to manage multiple fleets in an instance, even in premium tier")
 
 	// Conditional Access
 	man.addConfigString("conditional_access.cert_serial_format", "hex",