MM-31064: Simplify indentation (#16565)

* MM-31064: Simplify indentation

Reduce indentation where possible.

```release-note
NONE
```

Command ran to verify:
golangci-lint run --disable-all --enable golint --max-issues-per-linter=10000 --max-same-issues=100000 ./... | grep "block ends with a return state"

https://mattermost.atlassian.net/browse/MM-31064

* incorporate review comments

* enable golint for outdent rule

* fix remaining issues

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

store/storetest/plugin_store.go

@@ -728,9 +728,8 @@ func testPluginSetWithOptions(t *testing.T, ss store.Store, s SqlStore) {
 			ok, err := ss.Plugin().SetWithOptions(kv.PluginId, kv.Key, kv.Value, options)
 			if !ok {
 				return nil, err
-			} else {
-				return kv, err
 			}
+			return kv, err
 		})
 	})
 }

store/storetest/settings.go

@@ -29,9 +29,8 @@ const (
 func getEnv(name, defaultValue string) string {
 	if value := os.Getenv(name); value != "" {
 		return value
-	} else {
-		return defaultValue
 	}
+	return defaultValue
 }
 
 func log(message string) {