[e2e tests] fix regex for connection failures to catch a missed case (#36969)

Closes #36969

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/36969 from markdroth:e2e_test_regex_fix 043e5fdadb
PiperOrigin-RevId: 644540986

test/cpp/end2end/client_lb_end2end_test.cc

@@ -580,7 +580,8 @@ class ClientLbEnd2endTest : public ::testing::Test {
   }
 
   static std::string MakeConnectionFailureRegex(absl::string_view prefix) {
-    return absl::StrCat(prefix,
+    return absl::StrCat(
+        prefix,
         "; last error: (UNKNOWN|UNAVAILABLE): "
         // IP address
         "(ipv6:%5B::1%5D|ipv4:127.0.0.1):[0-9]+: "
@@ -588,7 +589,7 @@ class ClientLbEnd2endTest : public ::testing::Test {
         "(Failed to connect to remote host: )?"
         "(Timeout occurred: )?"
         // Syscall
-                        "((connect|recvmsg|getsockopt\\(SO\\_ERROR\\)): ?)?"
+        "((connect|sendmsg|recvmsg|getsockopt\\(SO\\_ERROR\\)): ?)?"
         // strerror() output or other message
         "(Connection refused"
         "|Connection reset by peer"

test/cpp/end2end/xds/xds_end2end_test_lib.cc

@@ -836,7 +836,8 @@ void XdsEnd2endTest::SetProtoDuration(
 
 std::string XdsEnd2endTest::MakeConnectionFailureRegex(
     absl::string_view prefix) {
-  return absl::StrCat(prefix,
+  return absl::StrCat(
+      prefix,
       "(UNKNOWN|UNAVAILABLE): "
       // IP address
       "(ipv6:%5B::1%5D|ipv4:127.0.0.1):[0-9]+: "
@@ -844,7 +845,7 @@ std::string XdsEnd2endTest::MakeConnectionFailureRegex(
       "(Failed to connect to remote host: )?"
       "(Timeout occurred: )?"
       // Syscall
-                      "((connect|recvmsg|getsockopt\\(SO\\_ERROR\\)): ?)?"
+      "((connect|sendmsg|recvmsg|getsockopt\\(SO\\_ERROR\\)): ?)?"
       // strerror() output or other message
       "(Connection refused"
       "|Connection reset by peer"