Remove automatic $ prefix for bash and console code blocks

[Turbo87]

This prefix is very surprising to blog authors because e.g. GitHub does not render it that way. It also does not work well if a code block contains multiple commands where all but the first one need a manual prefix. The original commit that introduced this unfortunately does not give any reasons for why it was introduced.

Related:

• Remove duplicate commandline prompt in console block displays #1260

r? @rust-lang/website

[kpreid]

The original commit that introduced this unfortunately does not give any reasons for why it was introduced.

One motivation might have been to cause the $ text to not be copiable, so that someone intending to copy and run the command doesn't get the $ that is not part of the command.