internal/prometheus: remove compose fail metrics

We have switched how 5xx errors are being recorded
internally and we are now recording all failures
for all endpoints. As a result, a dedicated metric
only for compose failures is no longer required.

internal/cloudapi/v2/errors.go

@@ -3,11 +3,8 @@ package v2
 import (
 	"fmt"
 	"net/http"
-	"strings"
 
 	"github.com/labstack/echo/v4"
-
-	"github.com/osbuild/osbuild-composer/internal/prometheus"
 )
 
 const (
@@ -302,13 +299,6 @@ func (s *Server) HTTPErrorHandler(echoError error, c echo.Context) {
 		return
 	}
 
-	internalError := he.Code >= http.StatusInternalServerError && he.Code <= http.StatusNetworkAuthenticationRequired
-	if internalError {
-		if strings.HasSuffix(c.Path(), "/compose") {
-			prometheus.ComposeFailures.Inc()
-		}
-	}
-
 	err, ok := he.Message.(detailsError)
 	if !ok {
 		// No service code was set, so Echo threw this error