[end2end] Shard some longer running tests a little more to reduce timeout risk (#33439)

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test/core/end2end/BUILD

@@ -312,7 +312,10 @@ grpc_core_end2end_test(name = "invoke_large_request")
 
 grpc_core_end2end_test(name = "keepalive_timeout")
 
-grpc_core_end2end_test(name = "large_metadata")
+grpc_core_end2end_test(
+    name = "large_metadata",
+    shard_count = 50,
+)
 
 grpc_core_end2end_test(name = "max_concurrent_streams")
 
@@ -423,7 +426,10 @@ grpc_core_end2end_test(name = "shutdown_finishes_calls")
 
 grpc_core_end2end_test(name = "shutdown_finishes_tags")
 
-grpc_core_end2end_test(name = "simple_delayed_request")
+grpc_core_end2end_test(
+    name = "simple_delayed_request",
+    shard_count = 50,
+)
 
 grpc_core_end2end_test(name = "simple_metadata")