Update package model/textparse tests for new labels.Labels type

We don't want to touch the result labels now we create them differently.

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>

model/textparse/openmetricsparse_test.go

@@ -246,7 +246,6 @@ foo_total 17.0 1520879607.789 # {xx="yy"} 5`
 				require.Equal(t, true, found)
 				require.Equal(t, *exp[i].e, e)
 			}
-			res = res[:0]
 
 		case EntryType:
 			m, typ := p.Type()

model/textparse/promparse_test.go

@@ -192,7 +192,6 @@ testmetric{label="\"bar\""} 1`
 			require.Equal(t, exp[i].t, ts)
 			require.Equal(t, exp[i].v, v)
 			require.Equal(t, exp[i].lset, res)
-			res = res[:0]
 
 		case EntryType:
 			m, typ := p.Type()
@@ -414,7 +413,7 @@ func BenchmarkParse(b *testing.B) {
 						case EntrySeries:
 							m, _, _ := p.Series()
 
-							res := make(labels.Labels, 0, 5)
+							var res labels.Labels
 							p.Metric(&res)
 
 							total += len(m)
@@ -426,7 +425,7 @@ func BenchmarkParse(b *testing.B) {
 			})
 			b.Run(parserName+"/decode-metric-reuse/"+fn, func(b *testing.B) {
 				total := 0
-				res := make(labels.Labels, 0, 5)
+				var res labels.Labels
 
 				b.SetBytes(int64(len(buf) / promtestdataSampleCount))
 				b.ReportAllocs()
@@ -451,7 +450,6 @@ func BenchmarkParse(b *testing.B) {
 
 							total += len(m)
 							i++
-							res = res[:0]
 						}
 					}
 				}

model/textparse/protobufparse_test.go

@@ -630,7 +630,6 @@ metric: <
 				require.Equal(t, true, found)
 				require.Equal(t, exp[i].e[0], e)
 			}
-			res = res[:0]
 
 		case EntryHistogram:
 			m, ts, shs, fhs := p.Histogram()
@@ -642,7 +641,6 @@ metric: <
 				require.Equal(t, exp[i].t, int64(0))
 			}
 			require.Equal(t, exp[i].lset, res)
-			res = res[:0]
 			require.Equal(t, exp[i].m, string(m))
 			if shs != nil {
 				require.Equal(t, exp[i].shs, shs)