Fix issue when switching submission's collection between those with different submission definition

[atarix83]

References

• Fixes Switching submission collection between ones with different submission definitions doesn't work #1234

Description

Fix issue when switching submission's collection between those with different submission definition

Instructions for Reviewers

Follow instruction present in the #1234 and check the issue is not present anymore

Checklist

• My PR is small in size (e.g. less than 1,000 lines of code, not including comments & specs/tests), or I have provided reasons as to why that's not possible.
• My PR passes TSLint validation using yarn run lint
• My PR doesn't introduce circular dependencies
• My PR includes TypeDoc comments for all new (or modified) public methods and classes. It also includes TypeDoc for large or complex private methods.
• My PR passes all specs/tests and includes new/updated specs or tests based on the Code Testing Guide.
• If my PR includes new, third-party dependencies (in package.json), I've made sure their licenses align with the DSpace BSD License based on the Licensing of Contributions documentation.

[tdonohue]

👍 Tested this by creating a submission for a default Item, then switching Collection to ones that had Entity specific forms...the new forms were loaded properly. Thanks @atarix83 !