upstream: fix typo (s/lb_type/lb_policy/g) in previous commit. (#4051)

While there, change to uppercase letters to match v2 style.

*Risk Level*: n/a
*Testing*: bazel test //test/...
*Docs Changes*: n/a
*Release Notes*: n/a

Signed-off-by: Piotr Sikora <piotrsikora@google.com>

test/common/upstream/original_dst_cluster_test.cc

@@ -488,8 +488,8 @@ TEST_F(OriginalDstClusterTest, UseHttpHeaderEnabled) {
   std::string yaml = R"EOF(
     name: "name"
     connect_timeout: 1.250s
-    type: original_dst
-    lb_type: original_dst_lb
+    type: ORIGINAL_DST
+    lb_policy: ORIGINAL_DST_LB
     original_dst_lb_config:
       use_http_header: true
   )EOF";
@@ -562,8 +562,8 @@ TEST_F(OriginalDstClusterTest, UseHttpHeaderDisabled) {
   std::string yaml = R"EOF(
     name: "name"
     connect_timeout: 1.250s
-    type: original_dst
-    lb_type: original_dst_lb
+    type: ORIGINAL_DST
+    lb_policy: ORIGINAL_DST_LB
   )EOF";
 
   EXPECT_CALL(initialized_, ready());