fix(slice-qos-config): use correct QoSConfig event constants in DeleteSliceQoSConfig metrics

[mdryaan]

Description

DeleteSliceQoSConfig in service/slice_qos_config_service.go was recording Prometheus counters with events.EventSliceConfigDeletionFailed (line 178) and events.EventSliceConfigDeleted (line 190) the SliceConfig constants instead of the QoSConfig-specific events.EventSliceQoSConfigDeletionFailed and events.EventSliceQoSConfigDeleted. The util.RecordEvent calls on the same lines already used the correct QoSConfig constants; only the metric counter labels were wrong. This caused all SliceQoSConfig deletion events to be counted under SliceConfig metric labels, making QoSConfig deletions invisible in QoS-specific dashboards and alerts.

Fixes #401

How Has This Been Tested?

• service/slice_qos_config_service.go:178 changed from events.EventSliceConfigDeletionFailed to events.EventSliceQoSConfigDeletionFailed; line 190 changed from events.EventSliceConfigDeleted to events.EventSliceQoSConfigDeleted. Verified by diffing against master.
• go build ./... passes.
• make fmt passes with no diff.
• Pre-existing make vet and make unit-test failures are present on unmodified master and are unrelated to this change.

Checklist:

• The title of the PR states what changed and the related issues number (used for the release note).
• Does this PR requires documentation updates? — No.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas. — N/A.
• I have tested it for all user roles. — N/A, metrics label fix.
• I have added all the required unit test cases.

Does this PR introduce a breaking change for other components like worker-operator?

No

Fix DeleteSliceQoSConfig recording Prometheus metrics under wrong SliceConfig event label names