Wait for mock metrics server to have started before running commands

Signed-off-by: Guillaume Tardif <guillaume.tardif@gmail.com>

tests/framework/mockmetrics.go

@@ -22,6 +22,7 @@ import (
 	"net"
 	"net/http"
 	"strings"
+	"time"
 
 	"github.com/labstack/echo"
 )
@@ -77,4 +78,7 @@ func (s *MockMetricsServer) Start() {
 		s.e.POST("/usage", s.handlePostUsage)
 		_ = s.e.Start(":1323")
 	}()
+
+	// wait a bit for the mock metrics server to actually listen
+	time.Sleep(500 * time.Millisecond)
 }