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/sqlstore/plugin_store.go

@@ -120,9 +120,8 @@ func (ps SqlPluginStore) CompareAndSet(kv *model.PluginKeyValue, oldValue []byte
 			// need to return it.
 			if IsUniqueConstraintError(err, []string{"PRIMARY", "PluginId", "Key", "PKey", "pkey"}) {
 				return false, nil
-			} else {
-				return false, errors.Wrap(err, "failed to insert PluginKeyValue")
 			}
+			return false, errors.Wrap(err, "failed to insert PluginKeyValue")
 		}
 	} else {
 		currentTime := model.GetMillis()

store/sqlstore/session_store.go

@@ -292,16 +292,16 @@ func (me SqlSessionStore) Cleanup(expiryTime int64, batchSize int64) {
 	var rowsAffected int64 = 1
 
 	for rowsAffected > 0 {
-		if sqlResult, err := me.GetMaster().Exec(query, map[string]interface{}{"ExpiresAt": expiryTime, "Limit": batchSize}); err != nil {
+		sqlResult, err := me.GetMaster().Exec(query, map[string]interface{}{"ExpiresAt": expiryTime, "Limit": batchSize})
+		if err != nil {
+			mlog.Error("Unable to cleanup session store.", mlog.Err(err))
+			return
+		}
+		var rowErr error
+		rowsAffected, rowErr = sqlResult.RowsAffected()
+		if rowErr != nil {
 			mlog.Error("Unable to cleanup session store.", mlog.Err(err))
 			return
-		} else {
-			var rowErr error
-			rowsAffected, rowErr = sqlResult.RowsAffected()
-			if rowErr != nil {
-				mlog.Error("Unable to cleanup session store.", mlog.Err(err))
-				return
-			}
 		}
 
 		time.Sleep(SESSIONS_CLEANUP_DELAY_MILLISECONDS * time.Millisecond)

store/sqlstore/user_store.go

@@ -518,9 +518,8 @@ func applyMultiRoleFilters(query sq.SelectBuilder, systemRoles []string, teamRol
 
 	if len(sqOr) > 0 {
 		return query.Where(sqOr)
-	} else {
-		return query
 	}
+	return query
 }
 
 func applyChannelGroupConstrainedFilter(query sq.SelectBuilder, channelId string) sq.SelectBuilder {