chore(bigtable): update the test proxy in accordance with the updated… (#7951)

… proto

Fixes: #7933
diff --git a/bigtable/internal/testproxy/proxy.go b/bigtable/internal/testproxy/proxy.go
index 7b5ec6d..441a9d2 100644
--- a/bigtable/internal/testproxy/proxy.go
+++ b/bigtable/internal/testproxy/proxy.go
@@ -594,7 +594,7 @@
 		Status: &statpb.Status{
 			Code: int32(codes.OK),
 		},
-		Row: []*btpb.Row{},
+		Rows: []*btpb.Row{},
 	}
 
 	if err != nil {
@@ -608,7 +608,7 @@
 		return res, nil
 	}
 
-	res.Row = rowsPb
+	res.Rows = rowsPb
 
 	return res, nil
 }
@@ -726,7 +726,7 @@
 		}
 	}
 
-	res.Entry = entries
+	res.Entries = entries
 	return res, nil
 }
 
@@ -838,7 +838,7 @@
 		sk = append(sk, s)
 	}
 
-	res.Sample = sk
+	res.Samples = sk
 
 	return res, nil
 }
diff --git a/bigtable/internal/testproxy/proxy_test.go b/bigtable/internal/testproxy/proxy_test.go
index bfd46ef..8f9fc74 100644
--- a/bigtable/internal/testproxy/proxy_test.go
+++ b/bigtable/internal/testproxy/proxy_test.go
@@ -260,8 +260,8 @@
 		t.Errorf("testproxy test: BulkMutateRows() didn't return OK; got %v", resp.Status.Code)
 	}
 
-	if len(resp.Entry) != 0 {
-		t.Errorf("testproxy test: BulkMutateRows() returned individual errors; got %v", resp.Entry)
+	if len(resp.Entries) != 0 {
+		t.Errorf("testproxy test: BulkMutateRows() returned individual errors; got %v", resp.Entries)
 	}
 }
 
@@ -315,8 +315,8 @@
 		t.Errorf("testproxy test: ReadRows() didn't return OK; got %v", resp.Status.Code)
 	}
 
-	if len(resp.Row) != 1 {
-		t.Errorf("testproxy test: SampleRowKeys() returned wrong number of results; got: %d", len(resp.Row))
+	if len(resp.Rows) != 1 {
+		t.Errorf("testproxy test: SampleRowKeys() returned wrong number of results; got: %d", len(resp.Rows))
 
 	}
 }
@@ -388,8 +388,8 @@
 		t.Errorf("testproxy test: SampleRowKeys() didn't return OK; got %v", resp.Status.Code)
 	}
 
-	if len(resp.Sample) != 1 {
-		t.Errorf("testproxy test: SampleRowKeys() returned wrong number of results; got: %d", len(resp.Sample))
+	if len(resp.Samples) != 1 {
+		t.Errorf("testproxy test: SampleRowKeys() returned wrong number of results; got: %d", len(resp.Samples))
 	}
 }