fix: do not enforce managed agent limit for non-task workspaces (#21689)

Only task workspaces have the checks in wsbuilder for violating the
managed agent caps in the license.

Stopped tasks that are resumed with a regular workspace start **still
count as usage**.

coderd/coderdtest/usage.go

@@ -0,0 +1,44 @@
+package coderdtest
+
+import (
+	"context"
+	"sync"
+
+	"github.com/coder/coder/v2/coderd/database"
+	"github.com/coder/coder/v2/coderd/usage"
+	"github.com/coder/coder/v2/coderd/usage/usagetypes"
+)
+
+var _ usage.Inserter = (*UsageInserter)(nil)
+
+type UsageInserter struct {
+	sync.Mutex
+	events []usagetypes.DiscreteEvent
+}
+
+func NewUsageInserter() *UsageInserter {
+	return &UsageInserter{
+		events: []usagetypes.DiscreteEvent{},
+	}
+}
+
+func (u *UsageInserter) InsertDiscreteUsageEvent(_ context.Context, _ database.Store, event usagetypes.DiscreteEvent) error {
+	u.Lock()
+	defer u.Unlock()
+	u.events = append(u.events, event)
+	return nil
+}
+
+func (u *UsageInserter) GetEvents() []usagetypes.DiscreteEvent {
+	u.Lock()
+	defer u.Unlock()
+	eventsCopy := make([]usagetypes.DiscreteEvent, len(u.events))
+	copy(eventsCopy, u.events)
+	return eventsCopy
+}
+
+func (u *UsageInserter) Reset() {
+	u.Lock()
+	defer u.Unlock()
+	u.events = []usagetypes.DiscreteEvent{}
+}