Refactor "implicit presence map behaviour" tests into its own file.

Also, change the proto used in no_field_presence_map_test into its own proto.
This should result in cleaner more isolated tests.

No other changes (other than autoformatter removing unused definitions).

PiperOrigin-RevId: 676927081

src/google/protobuf/BUILD.bazel

@@ -1782,6 +1782,20 @@ cc_test(
         ":protobuf",
         "@com_google_absl//absl/log:absl_check",
         "@com_google_absl//absl/memory",
+        "@com_google_absl//absl/strings:cord",
+        "@com_google_absl//absl/strings:string_view",
+        "@com_google_googletest//:gtest",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+cc_test(
+    name = "no_field_presence_map_test",
+    srcs = ["no_field_presence_map_test.cc"],
+    deps = [
+        ":cc_test_protos",
+        ":protobuf",
+        "@com_google_absl//absl/log:absl_check",
         "@com_google_absl//absl/strings",
         "@com_google_absl//absl/strings:cord",
         "@com_google_absl//absl/strings:string_view",

src/google/protobuf/unittest_no_field_presence.proto

@@ -100,11 +100,13 @@ message TestAllTypes {
     string oneof_string = 113;
     NestedEnum oneof_enum = 114;
   }
+}
 
-  map<int32, bytes> map_int32_bytes = 200;
-  map<int32, ForeignEnum> map_int32_foreign_enum = 201;
-  map<int32, ForeignMessage> map_int32_foreign_message = 202;
-  map<int32, ExplicitForeignMessage> map_int32_explicit_foreign_message = 203;
+message TestAllMapTypes {
+  map<int32, bytes> map_int32_bytes = 1;
+  map<int32, ForeignEnum> map_int32_foreign_enum = 2;
+  map<int32, ForeignMessage> map_int32_foreign_message = 3;
+  map<int32, ExplicitForeignMessage> map_int32_explicit_foreign_message = 4;
 }
 
 message TestProto2Required {