[internal/otelarrow] Remove manual time.Sleep call (#42548)

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#### Description

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Fixes
#42514

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Signed-off-by: Jared Tan <[email protected]>
Co-authored-by: Antoine Toulme <[email protected]>
Co-authored-by: Alex Boten <[email protected]>

Author: 3 people

internal/otelarrow/admission2/boundedqueue_test.go

@@ -67,12 +67,10 @@ func (bq *bqTest) startWaiter(ctx context.Context, size uint64, relp *ReleaseFun
 }
 
 func (bq *bqTest) waitForPending(admitted, waiting uint64) {
-	// TODO: Remove time.Sleep below, see https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/42514
-	time.Sleep(20 * time.Millisecond)
-	require.Eventually(bq.t, func() bool {
+	require.EventuallyWithT(bq.t, func(c *assert.CollectT) {
 		bq.lock.Lock()
 		defer bq.lock.Unlock()
-		return bq.currentAdmitted == admitted && bq.currentWaiting == waiting
+		assert.True(c, bq.currentAdmitted == admitted && bq.currentWaiting == waiting)
 	}, 10*time.Second, 20*time.Millisecond)
 }