Clear the environment in the cmd/webhooker tests that build a Config (closes #452)

TestNewApp_StopTimeout and TestNewApp_SendsFxEventsToTheLogger both
build the app graph, which runs config.New, so a variable exported in
the developer's shell reached them: METRICS_USERNAME without
METRICS_PASSWORD failed the second. Both now call
config.ClearEnvForTest before setting their own variables, as the
config tests and the gormlog first-boot test already do.

Model: opus-5-5

cmd/webhooker/main_test.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/webhooker/internal/config"
 	"sneak.berlin/go/webhooker/internal/datadir"
 	"sneak.berlin/go/webhooker/internal/resetpw"
 	"sneak.berlin/go/webhooker/internal/server"
@@ -36,6 +37,7 @@ const dockerStopGrace = 10 * time.Second
 // fx.New applies options before it executes invokes, so the timeout
 // is set whether or not the graph itself can be constructed here.
 func TestNewApp_StopTimeout(t *testing.T) {
+	config.ClearEnvForTest(t)
 	t.Setenv("DATA_DIR", t.TempDir())
 
 	got := newApp().StopTimeout()
@@ -73,6 +75,7 @@ func freePort(t *testing.T) int {
 // anything is built, and the run of logger.New, which happens before
 // the configuration sets the level.
 func TestNewApp_SendsFxEventsToTheLogger(t *testing.T) {
+	config.ClearEnvForTest(t)
 	t.Setenv("DATA_DIR", t.TempDir())
 	t.Setenv("PORT", strconv.Itoa(freePort(t)))
 	t.Setenv("DEBUG", "true")