chore: fix more non-constant format string errors

Author: karel-rehor

server/kapacitors.go

@@ -350,7 +350,7 @@ func (s *Service) deactivateOtherKapacitors(ctx context.Context, srcID int, ID i
 		}
 	}
 	if len(deactivationErrors) > 1 {
-		return fmt.Errorf(strings.Join(deactivationErrors, "\n"))
+		return fmt.Errorf("%s", strings.Join(deactivationErrors, "\n"))
 	}
 	return deactivationError
 }

server/mountable_router_test.go

@@ -24,7 +24,7 @@ func Test_MountableRouter_MountsRoutesUnderPrefix(t *testing.T) {
 
 	expected := "Hello?! McFly?! Anybody in there?!"
 	mr.GET("/biff", http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
-		fmt.Fprintf(rw, expected)
+		fmt.Fprintf(rw, "%s", expected)
 	}))
 
 	ts := httptest.NewServer(mr)

server/url_prefixer_test.go

@@ -180,7 +180,7 @@ func Test_Server_Prefixer_NoPrefixingWithoutFlusther(t *testing.T) {
 func Test_Server_Prefixer_IgnoreJsAndSvg(t *testing.T) {
 	expected := "Keep it the same please"
 	backend := http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
-		fmt.Fprintf(rw, expected)
+		fmt.Fprintf(rw, "%s", expected)
 	})
 
 	tl := &mocks.TestLogger{}