fix(inputs.netflow): Fallback to IPFIX mappings for Netflow v9

[srebhan]

Summary

Some devices send IPFIX elements encapsulated in Netflow v9 packets. As a workaround, this PR falls back to IPFIX mappings if none of the Netflow v9 or user mappings worked.

Checklist

• No AI generated code was used in this PR

Related issues

resolves #14902
resolves #14903

[telegraf-tiger]

Download PR build artifacts for linux_amd64.tar.gz, darwin_arm64.tar.gz, and windows_amd64.zip.
Downloads for additional architectures and packages are available below.

⚠️ This pull request increases the Telegraf binary size by 1.32 % for linux amd64 (new size: 227.6 MB, nightly size 224.6 MB)

📦 Click here to get additional PR build artifacts

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

[b0ch3nski]

@srebhan could you also bump github.com/netsampler/goflow2? Quite a lot of fixes done upstream.

[srebhan]

@b0ch3nski please checkout #14923! Let me know there if the bumped version works as expected!