fix(inputs.vault): Decode float values of gauges and counters

[skartikey]

Summary

Vault reports gauge values and the sum, min and max of counters as floating point numbers, but the plugin decoded them into integers. As soon as one of them has a fractional part, like vault.wal.write_controller.idle_secs in the linked issue, decoding the response fails and no metric is collected at all.

This PR always decodes those values as floats, so the response parses again. To avoid field type conflicts for existing users, the new float_values option defaults to false and keeps emitting integers by truncating the values, while float_values = true outputs the floats as reported by Vault. If the option is not set, a warning announces that the default changes to true in v1.45.0.

Checklist

• No AI generated code was used in this PR
• AI generated code used in this PR follows the InfluxData Policy on AI-Generated Code Contributions

Related issues

resolves #19672

[srebhan]

@skartikey we cannot do this change without a config setting as this will break nearly every user. Please add an option to keep ints by default with a warning about that the default for the option will change in say v1.45.0 outputting float values by default. We still keep the option to opt-out to the old types...
Then in v1.45.0 we deprecate the option for v1.50.0...

[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 6.05 % for linux amd64 (new size: 326.9 MB, nightly size 308.2 MB)

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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]

Thanks @skartikey!