tasks: Fail on error by default (run with `bash -e`)

Is your feature request related to a problem? Please describe

Gitpod multiline tasks don't fail if the failed command is in the middle (https://github.com/gitpod-io/gitpod/issues/13520).

For example, this inevitable failure will result in great success.

- init: |
    echo The failure is inevitable.
    true
    false
    true
    echo Unachievable great success."

Which is equivalent to this bash call.

$ bash -c "echo The failure is inevitable.   
  true
  false
  true
  echo Unachievable great success."
The failure is inevitable.
Unachievable great success.

https://github.com/gitpod-io/website/pull/2843 adds an explanation with a code snippet that users need to copy paste if they want to amend this behavior and fail on errors. The problem is, all other CI/CD systems that are configured by YAML, such as GitHub Actions, fail on multiline strings by default.

Describe the behaviour you'd like

The solution is to add -e option to bash when task is executed. Then the execution will be equal to this behavior.

$ bash -e -c "echo The failure is inevitable.
  true
  false
  true
  echo Unachievable great success."
The failure is inevitable.

The example at the https://github.com/gitpod-io/website/pull/2843 then could be altered to show how modify scripts to ignore failures.

Start by locating the Gitpod task execution path that invokes bash for multiline tasks, then compare its current behavior with the bash and bash -e examples in the issue. Done means multiline tasks stop after a failed command by default, with the documented example updated to explain how to ignore failures.