The `grpc.max_reconnect_backoff_ms` of client-c is too small to capture TLS verification errors

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

• After https://github.com/pingcap/tiflash/issues/9802

2. What did you expect to see? (Required)

3. What did you see instead (Required)

• The error logs of tiflash won't record valuable info (like Cannot check peer: missing selected ALPN property) again but only show messages like below

[2025/01/21 09:59:11.087 +00:00] [INFO] [Server.cpp:384] ["/workspace/source/tiflash/contrib/grpc/src/core/ext/filters/client_channel/subchannel.cc, line number: 945, log msg : subchannel 0x7821a7060800 {address=ipv4:10.0.128.40:10080, args=grpc.client_channel_factory=0x782c66a9d540, grpc.default_authority=db-tidb-0.db-tidb-peer.tidb1379661944646414117.svc:10080, grpc.http2_scheme=https, grpc.initial_reconnect_backoff_ms=1000, grpc.internal.channel_credentials=0x782bf05086f0, grpc.internal.security_connector=0x782bf0935130, grpc.internal.subchannel_pool=0x782c364c6aa0, grpc.max_receive_message_length=-1, grpc.max_reconnect_backoff_ms=3000, grpc.min_reconnect_backoff_ms=1000, grpc.primary_user_agent=grpc-c++/1.44.0, grpc.resource_quota=0x782c364c6b30, grpc.server_uri=dns:///db-tidb-0.db-tidb-peer.tidb1379661944646414117.svc:10080}: connect failed: {\"created\":\"@1737453551.087321880\",\"description\":\"Handshake read failed\",\"file\":\"/workspace/source/tiflash/contrib/grpc/src/core/lib/security/transport/security_handshaker.cc\",\"file_line\":457,\"referenced_errors\":[{\"created\":\"@1737453551.087299660\",\"description\":\"FD Shutdown\",\"file\":\"/workspace/source/tiflash/contrib/grpc/src/core/lib/iomgr/lockfree_event.cc\",\"file_line\":217,\"referenced_errors\":[{\"created\":\"@1737453551.087296828\",\"description\":\"Handshake timed out\",\"file\":\"/workspace/source/tiflash/contrib/grpc/src/core/lib/channel/handshaker.cc\",\"file_line\":165}]}]}"] [source=grpc] [thread_id=2762]
[2025/01/21 09:59:11.087 +00:00] [INFO] [Server.cpp:384] ["/workspace/source/tiflash/contrib/grpc/src/core/ext/filters/client_channel/subchannel.cc, line number: 884, log msg : subchannel 0x7821a7060800 {address=ipv4:10.0.128.40:10080, args=grpc.client_channel_factory=0x782c66a9d540, grpc.default_authority=db-tidb-0.db-tidb-peer.tidb1379661944646414117.svc:10080, grpc.http2_scheme=https, grpc.initial_reconnect_backoff_ms=1000, grpc.internal.channel_credentials=0x782bf05086f0, grpc.internal.security_connector=0x782bf0935130, grpc.internal.subchannel_pool=0x782c364c6aa0, grpc.max_receive_message_length=-1, grpc.max_reconnect_backoff_ms=3000, grpc.min_reconnect_backoff_ms=1000, grpc.primary_user_agent=grpc-c++/1.44.0, grpc.resource_quota=0x782c364c6b30, grpc.server_uri=dns:///db-tidb-0.db-tidb-peer.tidb1379661944646414117.svc:10080}: Retry immediately"] [source=grpc] [thread_id=2762]
[2025/01/21 09:59:11.087 +00:00] [INFO] [Server.cpp:384] ["/workspace/source/tiflash/contrib/grpc/src/core/ext/filters/client_channel/subchannel.cc, line number: 910, log msg : subchannel 0x7821a7060800 {address=ipv4:10.0.128.40:10080, args=grpc.client_channel_factory=0x782c66a9d540, grpc.default_authority=db-tidb-0.db-tidb-peer.tidb1379661944646414117.svc:10080, grpc.http2_scheme=https, grpc.initial_reconnect_backoff_ms=1000, grpc.internal.channel_credentials=0x782bf05086f0, grpc.internal.security_connector=0x782bf0935130, grpc.internal.subchannel_pool=0x782c364c6aa0, grpc.max_receive_message_length=-1, grpc.max_reconnect_backoff_ms=3000, grpc.min_reconnect_backoff_ms=1000, grpc.primary_user_agent=grpc-c++/1.44.0, grpc.resource_quota=0x782c364c6b30, grpc.server_uri=dns:///db-tidb-0.db-tidb-peer.tidb1379661944646414117.svc:10080}: failed to connect to channel, retrying"] [source=grpc] [thread_id=2762]

The default grpc.max_reconnect_backoff_ms(3000 ms) is much smaller than DEFAULT_POLL_INTERVAL_MS(5000 ms). When facing error about TLS connection verification, the backup poller ( sync mod API ) can not capture valuable info in time before next reconnection.

4. What is your TiFlash version? (Required)

after https://github.com/pingcap/tiflash/pull/3649

>= v5.4.0

Start by tracing the backup poller (sync mod API) and its DEFAULT_POLL_INTERVAL_MS alongside gRPC's client_channel/subchannel.cc handling of grpc.max_reconnect_backoff_ms. Confirm how TLS verification failures are logged before reconnection, then define the change and validate that valuable verification errors remain observable across reconnect attempts.