stackdriver: remove not used query file

pkg/tsdb/stackdriver/default_project_query.go

-package stackdriver
-
-import (
-	"context"
-
-	"github.com/grafana/grafana/pkg/components/simplejson"
-	"github.com/grafana/grafana/pkg/tsdb"
-)
-
-func (e *StackdriverExecutor) getGceDefaultProject(ctx context.Context, tsdbQuery *tsdb.TsdbQuery) (*tsdb.Response, error) {
-	queryResult := &tsdb.QueryResult{Meta: simplejson.New(), RefId: tsdbQuery.Queries[0].RefId}
-	result := &tsdb.Response{
-		Results: make(map[string]*tsdb.QueryResult),
-	}
-	defaultProject, err := e.getDefaultProject(ctx)
-	if err != nil {
-		return nil, err
-	}
-	queryResult.Meta.Set("defaultProject", defaultProject)
-	result.Results[tsdbQuery.Queries[0].RefId] = queryResult
-	return result, nil
-}