fix(queue): reset projection list before each Register call (#10001)

# Which Problems Are Solved

if Zitadel was started using `start-from-init` or `start-from-setup`
there were rare cases where a panic occured when
`Notifications.LegacyEnabled` was set to false. The cause was a list
which was not reset before refilling.

# How the Problems Are Solved

The list is now reset before each time it gets filled.

# Additional Changes

Ensure all contexts are canceled for the init and setup functions for
`start-from-init- or `start-from-setup` commands.

# Additional Context

none

cmd/start/start_from_init.go

@@ -1,6 +1,8 @@
 package start
 
 import (
+	"context"
+
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 	"github.com/zitadel/logging"
@@ -29,14 +31,19 @@ Requirements:
 			masterKey, err := key.MasterKey(cmd)
 			logging.OnError(err).Panic("No master key provided")
 
-			initialise.InitAll(cmd.Context(), initialise.MustNewConfig(viper.GetViper()))
+			initCtx, cancel := context.WithCancel(cmd.Context())
+			initialise.InitAll(initCtx, initialise.MustNewConfig(viper.GetViper()))
+			cancel()
 
 			err = setup.BindInitProjections(cmd)
 			logging.OnError(err).Fatal("unable to bind \"init-projections\" flag")
 
 			setupConfig := setup.MustNewConfig(viper.GetViper())
 			setupSteps := setup.MustNewSteps(viper.New())
-			setup.Setup(cmd.Context(), setupConfig, setupSteps, masterKey)
+
+			setupCtx, cancel := context.WithCancel(cmd.Context())
+			setup.Setup(setupCtx, setupConfig, setupSteps, masterKey)
+			cancel()
 
 			startConfig := MustNewConfig(viper.GetViper())
 

cmd/start/start_from_setup.go

@@ -1,6 +1,8 @@
 package start
 
 import (
+	"context"
+
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 	"github.com/zitadel/logging"
@@ -34,7 +36,10 @@ Requirements:
 
 			setupConfig := setup.MustNewConfig(viper.GetViper())
 			setupSteps := setup.MustNewSteps(viper.New())
-			setup.Setup(cmd.Context(), setupConfig, setupSteps, masterKey)
+
+			setupCtx, cancel := context.WithCancel(cmd.Context())
+			setup.Setup(setupCtx, setupConfig, setupSteps, masterKey)
+			cancel()
 
 			startConfig := MustNewConfig(viper.GetViper())
 

internal/notification/projections.go

@@ -46,6 +46,9 @@ func Register(
 		queue.ShouldStart()
 	}
 
+	// make sure the slice does not contain old values
+	projections = nil
+
 	q := handlers.NewNotificationQueries(queries, es, externalDomain, externalPort, externalSecure, fileSystemPath, userEncryption, smtpEncryption, smsEncryption)
 	c := newChannels(q)
 	projections = append(projections, handlers.NewUserNotifier(ctx, projection.ApplyCustomConfig(userHandlerCustomConfig), commands, q, c, otpEmailTmpl, notificationWorkerConfig, queue))