fix(inputs.phpfpm): Add timeout for fcgi

[PierreF]

Summary

The input PHP-FPM don't have timeout when talking (F)CGI protocol, which could lead to input blocked forever.

The timeout exists and was used for HTTP, but not for fcgi.

Checklist

• No AI generated code was used in this PR

Related issues

resolves #15035

[srebhan]

@PierreF thanks for fixing this issue! Could you please add a unit-test for the timeout?!?

[PierreF]

I've added the test in the same commit (I'm unsure if you prefer a single commit with code & test or if you prefer avoid push force).
The error seems unrelated to my change: it's on syslog input and phpfpm input test passed.

[srebhan]

Some comments regarding the unit-test...

[telegraf-tiger]

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Downloads for additional architectures and packages are available below.

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Artifact URLs

DEB	RPM	TAR GZ	ZIP
amd64.deb	aarch64.rpm	darwin_amd64.tar.gz	windows_amd64.zip
arm64.deb	armel.rpm	darwin_arm64.tar.gz	windows_arm64.zip
armel.deb	armv6hl.rpm	freebsd_amd64.tar.gz	windows_i386.zip
armhf.deb	i386.rpm	freebsd_armv7.tar.gz
i386.deb	ppc64le.rpm	freebsd_i386.tar.gz
mips.deb	riscv64.rpm	linux_amd64.tar.gz
mipsel.deb	s390x.rpm	linux_arm64.tar.gz
ppc64el.deb	x86_64.rpm	linux_armel.tar.gz
riscv64.deb		linux_armhf.tar.gz
s390x.deb		linux_i386.tar.gz
		linux_mips.tar.gz
		linux_mipsel.tar.gz
		linux_ppc64le.tar.gz
		linux_riscv64.tar.gz
		linux_s390x.tar.gz

[srebhan]

Awesome! Thanks @PierreF!