fix(meshhttproute): deref pointer to weight or use default 1

[lukidzi]

Checklist prior to review

Kubebuilder generates OpenAPI spec with defaults; once we don't set it, it is set to the default from the spec. Unfortunately, it doesn't work on Universal, and the value might not be set correctly. Because of this once dereferencing weight, we hit the nil pointer. #6070

Logs

	OnTick() failed	{"dataplaneKey": {"Mesh":"default","Name":"gateway-instance-1"}, "error": "runtime error: invalid memory address or nil pointer dereference", "errorVerbose": "runtime error: invalid memory address or nil pointer dereference\ngithub.com/kumahq/kuma/pkg/util/watchdog.(*SimpleWatchdog).onTick.func1\n\tgithub.com/kumahq/kuma/pkg/util/watchdog/watchdog.go:62\nruntime.gopanic\n\truntime/panic.go:770\nruntime.panicmem\n\truntime/panic.go:261\nruntime.sigpanic\n\truntime/signal_unix.go:881\ngithub.com/kumahq/kuma/pkg/plugins/policies/meshhttproute/plugin/v1alpha1.makeHttpRouteEntry\n\tgithub.com/kumahq/kuma/pkg/plugins/policies/meshhttproute/plugin/v1alpha1/gateway_routes.go:220\ngithub.com/kumahq/kuma/pkg/plugins/policies/meshhttproute/plugin/v1alpha1.generateEnvoyRouteEntries\n\tgithub.com/kumahq/kuma/pkg/plugins/policies/meshhttproute/plugin/v1alpha1/gateway_routes.go:180\ngithub.com/kumahq/kuma/pkg/plugins/policies/meshhttproute/plugin/v1alpha1.sortRulesToHosts\n\tgithub.com/kumahq/kuma/pkg/plugins/policies/meshhttproute/plugin/v1alpha1/gateway_routes.go:147\ngithub.com/kumahq/kuma/pkg/plugins/policies/core/xds/meshroute.CollectListenerInfos\n\tgithub.com/kumahq/kuma/pkg/plugins/policies/core/xds/meshroute/gateway.go:100\ngithub.com/kumahq/kuma/pkg/plugins/policies/meshhttproute/plugin/v1alpha1.ApplyToGateway\n\tgithub.com/kumahq/kuma/pkg/plugins/policies/meshhttproute/plugin/v1alpha1/plugin.go:126\ngithub.com/kumahq/kuma/pkg/plugins/policies/meshhttproute/plugin/v1alpha1.plugin.Apply\n\tgithub.com/kumahq/kuma/pkg/plugins/policies/meshhttproute/plugin/v1alpha1/plugin.go:62\ngithub.com/kumahq/kuma/pkg/plugins/policies/core/generator.generator.Generate\n\tgithub.com/kumahq/kuma/pkg/plugins/policies/core/generator/generator.go:23\ngithub.com/kumahq/kuma/pkg/xds/generator/core.CompositeResourceGenerator.Generate\n\tgithub.com/kumahq/kuma/pkg/xds/generator/core/resource_generator.go:22\ngithub.com/kumahq/kuma/pkg/xds/generator.(*ProxyTemplateProfileSource).Generate\n\tgithub.com/kumahq/kuma/pkg/xds/generator/proxy_template.go:76\ngithub.com/kumahq/kuma/pkg/xds/generator.(*ProxyTemplateGenerator).Generate\n\tgithub.com/kumahq/kuma/pkg/xds/generator/proxy_template.go:28\ngithub.com/kumahq/kuma/pkg/xds/server/v3.(*TemplateSnapshotGenerator).GenerateSnapshot\n\tgithub.com/kumahq/kuma/pkg/xds/server/v3/reconcile.go:167\ngithub.com/kumahq/kuma/pkg/xds/server/v3.(*reconciler).Reconcile\n\tgithub.com/kumahq/kuma/pkg/xds/server/v3/reconcile.go:55\ngithub.com/kumahq/kuma/pkg/xds/sync.(*DataplaneWatchdog).syncDataplane\n\tgithub.com/kumahq/kuma/pkg/xds/sync/dataplane_watchdog.go:166\ngithub.com/kumahq/kuma/pkg/xds/sync.(*DataplaneWatchdog).Sync\n\tgithub.com/kumahq/kuma/pkg/xds/sync/dataplane_watchdog.go:80\ngithub.com/kumahq/kuma/pkg/xds/sync.(*dataplaneWatchdogFactory).New.func2\n\tgithub.com/kumahq/kuma/pkg/xds/sync/dataplane_watchdog_factory.go:43\ngithub.com/kumahq/kuma/pkg/util/watchdog.(*SimpleWatchdog).onTick\n\tgithub.com/kumahq/kuma/pkg/util/watchdog/watchdog.go:70\ngithub.com/kumahq/kuma/pkg/util/watchdog.(*SimpleWatchdog).Start\n\tgithub.com/kumahq/kuma/pkg/util/watchdog/watchdog.go:40\nruntime.goexit\n\truntime/asm_arm64.s:1222"}

• Link to relevant issue as well as docs and UI issues --
• This will not break child repos: it doesn't hardcode values (.e.g "kumahq" as a image registry) and it will work on Windows, system specific functions like syscall.Mkfifo have equivalent implementation on the other OS --
• Tests (Unit test, E2E tests, manual test on universal and k8s) --
  • Don't forget ci/ labels to run additional/fewer tests
• Do you need to update UPGRADE.md? --
• Does it need to be backported according to the backporting policy? (this GH action will add "backport" label based on these file globs, if you want to prevent it from adding the "backport" label use no-backport-autolabel label) --

[github-actions]

backporting to release-2.5 with action

backporting to release-2.6 with action
backporting to release-2.4 with action
backporting to release-2.7 with action
backporting to release-2.8 with action