Show installed toolchains if a user tries to set an incorrect toolchain name to the default. #1981

Job	Run time
cancel-previous-runs	4s
check-scripts	9s
cargo-fmt-check	11s
cargo-clippy	19s
Try fuelup installation with fuelup-init (ubuntu-latest)	14s
cargo-test-workspace	1m 14s
lint-toml-files	15s
Try fuelup installation with fuelup-init (macos-latest)	20s
build fuelup release binaries	0s
Do post-release checks	0s
publish-check	0s
	2m 46s

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