See #10925

Fixes #10925

BREAKING CHANGE: the following deprecated plugins have been removed:
`cargo`, `copydir`, `npx`, `osx`, and `rustup`. See the wiki for more info:
https://github.com/ohmyzsh/ohmyzsh/wiki/Plugins#removed

refactor(rustup)!: remove deprecated plugin

BREAKING CHANGE: the plugin was deprecated and is now removed. See the wiki for more info:
https://github.com/ohmyzsh/ohmyzsh/wiki/Plugins#removed

Closes #10939

Co-authored-by: Jorge Francisco Varela Gutiérrez <jvarela@jfvarela.redhat.com>

Co-authored-by: Steven Pitts <spitts@teikametrics.com>

Fixes https://github.com/ohmyzsh/ohmyzsh/commit/140c977a3d82410f48c198596de193d2d6b7b9b5#commitcomment-73688165

Fixes #10884
Closes #10910

Fixes #10884

BREAKING CHANGE: the boot2docker project was abandoned in 2020,
so it makes no sense to keep the plugin. If you were using it,
remove it from the `$plugins` array.

Fixes #10877

Fixes #10878

Since `set -e` is enabled, when `commit.gpgsign` is not set the
`git config` command would show an error. Given that it is technically
not ignored, the subshell would exit.

With this change, the `commit.gpgsign` setting is properly tested
by doing the fallback test if the command fails, so no exit status
code ends up quiting the subshell.