chore(parser.json_v2): Error out if no config is provided

[mskonovalov]

Summary

Making json_v2 parser fail to initialize, if there are no configured fields or tags as there is no chance this parser will ever produce a metric in this state.

Checklist

• No AI generated code was used in this PR

Related issues

superseeds #15840

[srebhan]

Thanks for the PR @mskonovalov! Please remove the parser type from the error message as this will be automatically added by the logger. Furthermore, it would be nice to add a hint to this behavioral change in the CHANGELOG.md file (see this example).

[mskonovalov]

there are a few tests that are failing which I may need some help fixing :)

[srebhan]

I guess you just need to provide a rudimentary config there. Also please add a test for your new error!

[srebhan]

Thank you very much @mskonovalov!

[telegraf-tiger]

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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