Rename QuicDefaultEventLoop to QuicPollEventLoop.

This better reflects what the class actually does, and I am working on code that lets us override the default via a platform API, making this name inaccurate.

PiperOrigin-RevId: 456834349
diff --git a/build/source_list.bzl b/build/source_list.bzl
index aaf08ad..4d1ff62 100644
--- a/build/source_list.bzl
+++ b/build/source_list.bzl
@@ -932,8 +932,8 @@
     "quic/core/batch_writer/quic_batch_writer_test.h",
     "quic/core/batch_writer/quic_gso_batch_writer.h",
     "quic/core/batch_writer/quic_sendmmsg_batch_writer.h",
-    "quic/core/io/quic_default_event_loop.h",
     "quic/core/io/quic_event_loop.h",
+    "quic/core/io/quic_poll_event_loop.h",
     "quic/core/quic_default_packet_writer.h",
     "quic/core/quic_epoll_alarm_factory.h",
     "quic/core/quic_epoll_clock.h",
@@ -964,7 +964,7 @@
     "quic/core/batch_writer/quic_batch_writer_buffer.cc",
     "quic/core/batch_writer/quic_gso_batch_writer.cc",
     "quic/core/batch_writer/quic_sendmmsg_batch_writer.cc",
-    "quic/core/io/quic_default_event_loop.cc",
+    "quic/core/io/quic_poll_event_loop.cc",
     "quic/core/quic_default_packet_writer.cc",
     "quic/core/quic_epoll_alarm_factory.cc",
     "quic/core/quic_epoll_clock.cc",
@@ -1278,7 +1278,7 @@
     "quic/core/http/quic_spdy_client_session_test.cc",
     "quic/core/http/quic_spdy_client_stream_test.cc",
     "quic/core/http/quic_spdy_server_stream_base_test.cc",
-    "quic/core/io/quic_default_event_loop_test.cc",
+    "quic/core/io/quic_poll_event_loop_test.cc",
     "quic/core/quic_epoll_alarm_factory_test.cc",
     "quic/core/quic_epoll_clock_test.cc",
     "quic/core/quic_epoll_connection_helper_test.cc",