[addon-operator] add queue head info metric and critical flag to module info

[diyliv]

What this PR does

Adds two metrics that let us replace the flat D8DeckhouseQueueIsHung alert with severity-differentiated alerts.

New metric: tasks_queue_head_info

A gauge (value=1) with labels queue, module, task_type, hook. Published every 5 seconds for each non-empty queue. Old series are expired when the head changes -> no phantom metrics remain.

Label cleanup:

• ParallelModuleRun synthetic names like "Parallel run for a, b, c" -> normalized to empty string (would otherwise produce a bad join with deckhouse_mm_module_info)
• Global tasks (ConvergeModules, GlobalHookRun, DiscoverHelmReleases, ApplyKubeConfigValues) -> module is empty, which is correct since these are not module-specific

New label: critical on deckhouse_mm_module_info

Value "true" or "false" from BasicModule.GetCritical() (the critical: true property in module.yaml). Added additively -> existing queries are unaffected.

Why it's needed

The old D8DeckhouseQueueIsHung alert had two problems:

• No way to see what's stuck -> only the queue name was visible, not the module, task type, or hook
• Same severity for everything -> all hung queues alerted at severity 7 regardless of how critical the module was

With these two metrics, we can create three separate alerts:

Alert	Severity	Triggers for
D8DeckhouseQueueIsHungCritical	4	critical="true" modules
D8DeckhouseQueueIsHung	6	critical="false" modules
D8DeckhouseQueueIsHungGlobal	4	global tasks (module="")