resolve socket leak in fluentd exporter

[KSSKarthikeya]

fluentd_exporter.cc Connect() function is causing socket leak when the connection fails.

Test results: Open FDs count stopped increasing after fix.

Every 2.0s: /workspace/pid_watch.sh                                                                qemux86-64: Fri Oct  3 20:15:02 2025

Time: 2025-10-03 20:15:02  PID: 1827
---- /proc/1827/limits ----
Limit                     Soft Limit           Hard Limit           Units
Max open files            1024                 4096                 files
---- FD usage ----
open_fds: 11  max_fds: 1024 4096
---- Socket counts (tcp/udp/unix) ----
tcp lines: 14
udp lines: 4
unix lines: 11

Every 2.0s: /workspace/pid_watch.sh                                                                  qemux86-64: Fri Oct  3 20:16:59 2025

Time: 2025-10-03 20:16:59  PID: 1827
---- /proc/1827/limits ----
Limit                     Soft Limit           Hard Limit           Units
Max open files            1024                 4096                 files

---- FD usage ----
open_fds: 11  max_fds: 1024 4096
---- Socket counts (tcp/udp/unix) ----
tcp lines: 14
udp lines: 4
unix lines: 11

[linux-foundation-easycla]

• ✅login: KSSKarthikeya / name: Karthikeya K S S / (6823050)
• ✅login: KSSKarthikeya / name: Karthikeya K S S / (6823050, 991f0cb)

The committers listed above are authorized under a signed CLA.

[ThomsonTan]

Is this set of connected_ to false necessary? Seems unnecessary because it is already in false.

[KSSKarthikeya]

@ThomsonTan , thanks for pointing that out, I have removed it.
Can this be approved ?