fix: reimplement reporting of preset-hard-limited metric (#18055)

Addresses concerns raised in https://github.com/coder/coder/pull/18045

coderd/prebuilds/global_snapshot.go

@@ -12,11 +12,11 @@ import (
 
 // GlobalSnapshot represents a full point-in-time snapshot of state relating to prebuilds across all templates.
 type GlobalSnapshot struct {
-	Presets             []database.GetTemplatePresetsWithPrebuildsRow
-	RunningPrebuilds    []database.GetRunningPrebuiltWorkspacesRow
-	PrebuildsInProgress []database.CountInProgressPrebuildsRow
-	Backoffs            []database.GetPresetsBackoffRow
-	HardLimitedPresets  []database.GetPresetsAtFailureLimitRow
+	Presets               []database.GetTemplatePresetsWithPrebuildsRow
+	RunningPrebuilds      []database.GetRunningPrebuiltWorkspacesRow
+	PrebuildsInProgress   []database.CountInProgressPrebuildsRow
+	Backoffs              []database.GetPresetsBackoffRow
+	HardLimitedPresetsMap map[uuid.UUID]database.GetPresetsAtFailureLimitRow
 }
 
 func NewGlobalSnapshot(
@@ -26,12 +26,17 @@ func NewGlobalSnapshot(
 	backoffs []database.GetPresetsBackoffRow,
 	hardLimitedPresets []database.GetPresetsAtFailureLimitRow,
 ) GlobalSnapshot {
+	hardLimitedPresetsMap := make(map[uuid.UUID]database.GetPresetsAtFailureLimitRow, len(hardLimitedPresets))
+	for _, preset := range hardLimitedPresets {
+		hardLimitedPresetsMap[preset.PresetID] = preset
+	}
+
 	return GlobalSnapshot{
-		Presets:             presets,
-		RunningPrebuilds:    runningPrebuilds,
-		PrebuildsInProgress: prebuildsInProgress,
-		Backoffs:            backoffs,
-		HardLimitedPresets:  hardLimitedPresets,
+		Presets:               presets,
+		RunningPrebuilds:      runningPrebuilds,
+		PrebuildsInProgress:   prebuildsInProgress,
+		Backoffs:              backoffs,
+		HardLimitedPresetsMap: hardLimitedPresetsMap,
 	}
 }
 
@@ -66,9 +71,7 @@ func (s GlobalSnapshot) FilterByPreset(presetID uuid.UUID) (*PresetSnapshot, err
 		backoffPtr = &backoff
 	}
 
-	_, isHardLimited := slice.Find(s.HardLimitedPresets, func(row database.GetPresetsAtFailureLimitRow) bool {
-		return row.PresetID == preset.ID
-	})
+	_, isHardLimited := s.HardLimitedPresetsMap[preset.ID]
 
 	return &PresetSnapshot{
 		Preset:        preset,
@@ -80,6 +83,12 @@ func (s GlobalSnapshot) FilterByPreset(presetID uuid.UUID) (*PresetSnapshot, err
 	}, nil
 }
 
+func (s GlobalSnapshot) IsHardLimited(presetID uuid.UUID) bool {
+	_, isHardLimited := s.HardLimitedPresetsMap[presetID]
+
+	return isHardLimited
+}
+
 // filterExpiredWorkspaces splits running workspaces into expired and non-expired
 // based on the preset's TTL.
 // If TTL is missing or zero, all workspaces are considered non-expired.