fix!: Remove deprecated settings functionality for output plugins

[sspaink]

DON'T MERGE TO MASTER, the strategy will be to merge all breaking changes to a separate branch.

Remove the deprecated settings for output plugins listed in #9478. Since this breaks compatibility, it will not be merged until the next major release (2.0).

Semantic PR checker is failing because: influxdata/validate-semantic-github-messages#20

[sspaink]

TODO: Don't delete settings from struct to maintain deprecation messages

[telegraf-tiger]

Download PR build artifacts for linux_amd64.tar.gz, darwin_amd64.tar.gz, and windows_amd64.zip.
Downloads for additional architectures and packages are available below.

☺️ This pull request doesn't significantly change the Telegraf binary size (less than 1%)

📦 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_i386.zip
armel.deb	armv6hl.rpm	freebsd_amd64.tar.gz
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
		static_linux_amd64.tar.gz

[powersj]

As we are not planning on doing a Telegraf 2.x at this time anymore, I am closing breaking changes issues and PRs. While we have interest in making these improvements we currently, and for the foreseeable future do not have the capital to maintain two major versions while also supporting our users at the same level.