Fixed parsing of relative paths for MDM profiles in gitops no-team.yml (#26046)

For #25770 

We already unmarshal macOS/Windows settings (added by Martin), so we
replace the path with an absolute file path and keep them unmarshalled
so they don't have to be re-unmarshalled later. Note: the custom
UnmarshalJSON method on these structs checks for (and handles) legacy
format (before labels were added).

Also some refactorings:
- extracted `extractControlsForNoTeam`
- reorganized `TestGitOpsBasicGlobalAndNoTeam` with subtests -- I did
not actually change functionality of this test

# Checklist for submitter

- [x] 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/Committing-Changes.md#changes-files)
for more information.
- [x] Added/updated automated tests
- [x] A detailed QA plan exists on the associated ticket (if it isn't
there, work with the product group's QA engineer to add it)
- [x] Manual QA for all new/changed functionality

pkg/spec/gitops_test.go

@@ -218,9 +218,9 @@ func TestValidGitOpsYaml(t *testing.T) {
 				}
 
 				// Check controls
-				_, ok := gitops.Controls.MacOSSettings.(map[string]interface{})
+				_, ok := gitops.Controls.MacOSSettings.(fleet.MacOSSettings)
 				assert.True(t, ok, "macos_settings not found")
-				_, ok = gitops.Controls.WindowsSettings.(map[string]interface{})
+				_, ok = gitops.Controls.WindowsSettings.(fleet.WindowsSettings)
 				assert.True(t, ok, "windows_settings not found")
 				_, ok = gitops.Controls.EnableDiskEncryption.(bool)
 				assert.True(t, ok, "enable_disk_encryption not found")