Tests: write a test for removing/adding inputs on a procedure & caller block

[alschmiedt]

Is your feature request related to a problem? Please describe.
There was a bug in core where callers would break when an input was removed. This was only caught because of tests in samples.

We should look at pulling some of those into core.

Describe the solution you'd like
Not entirely sure yet. Depending on how this issue goes we might want to look at following the same pattern. Where we create a set of procedure tests that blockly supplies and plugins can also run.

Describe alternatives you've considered
The simple solution is to just copy and paste the test into core.

Additional context

[rachel-fenichel]

Fixed during @BeksOmega's procedure work.