Warn the user that using `-i`/`-u`/`-d` will overwrite everything about their scenarios

[mstoykov]

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Feature Description

Users are sometimes confused why using -i, -u or/and -d works the way it does. This includes both why does it suddenly not use their exec function ([citation needed]) or why they don't use the env they have defined.

While there are some indications that we no longer run the same scenarios, it likely will be nice to be more explicit.

p.s. forgot about -s for stages, as I never see it used :facepalm:

Suggested Solution (optional)

On usage of any of the shortcut options - print a warning stating that this will completely overwrite the whole options.scenarios possibly somewhere in https://github.com/grafana/k6/blob/c055402af97ee7e403edeb13396a49185e304365/lib/executor/execution_config_shortcuts.go#L72

Already existing or connected issues / PRs (optional)

No response