Backport(v1.16): Fix #4396: Add timeout to establish_connection to prevent infinite loop (#5104)

[Watson1978]

Backport #5104

Which issue(s) this PR fixes:
Fixes #4396

What this PR does / why we need it:
Adds timeout mechanism to establish_connection method to prevent infinite loop when handshake protocol gets stuck. In unstable network environments with proxy components, if connection drops during handshake after TLS establishment, Fluentd gets stuck in infinite loop causing logs to stop being flushed. This fix uses existing hard_timeout configuration to break the loop, disable problematic nodes, and maintain log flow through healthy nodes.

Docs Changes:
None required - uses existing hard_timeout configuration parameter.

Release Note:
out_forward: fix issue where could cause output to stop when using <security> and TLS setting together under unstable network environments

[ashie]

Same status with #5138 (comment)

Hmm, we need to investigate the CI failure in https://github.com/fluent/fluentd/actions/runs/19123383854/job/54648369661

1) Error: test: Node with security is thread-safe on multi threads(ForwardOutputTest): TypeError: wrong argument type nil (expected Data)
C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/cool.io-1.9.0/lib/cool.io/loop.rb:88:in `run_once'
C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/cool.io-1.9.0/lib/cool.io/loop.rb:88:in `run'
D:/a/fluentd/fluentd/lib/fluent/plugin_helper/event_loop.rb:93:in `block in start'
D:/a/fluentd/fluentd/lib/fluent/plugin_helper/thread.rb:78:in `block in thread_create'

So, we discussed that this backport will be released at 1.19.2 or later.

[Watson1978]

Without this change, it appears to fail sometimes in the v1.16 branch as well....

[kenhys]

For a last milestone of v1.16, it might be reasonable.