stop adding then replacing port 8001 in mock builds

[tomholub]

I suppose it could.. we would still need to do two rounds of replacing? The step that normally replaces [BUILD_REPLACEABLE_....] and currently puts the :8001 would still need to insert some more maybe [TEST_REPLACEABLE_MOCK_PORT] and then that would be replaced here.

It's true that as things are now, there is no meaning to the :8001 in particular. So that should not be put it, to not be confusing. So [TEST_REPLACEABLE_MOCK_PORT] or similar would be a better choice here.

Originally posted by @tomholub in #4928 (comment)

[tomholub]

[rrrooommmaaa]

I suggest to also implement removing the lines that have this token, e.g. the line
email = email.replace(/\:[TEST_REPLACEABLE_MOCK_PORT]$/, '');
would ideally disappear from the production build.

[tomholub]

ok. that's a separate issue, let's file it separately. agree with it though in principle. need to check exactly which things does such change touch