[Create_Timepoint] MRI time point error fix #8923

[fias06]

Brief summary of changes

Error messaged changed to "For MRI visit, please select a scanning site. Scanning sites are identified with (MRI).". The site does not auto populate, the inputs are blank at first and allows user to select.
The error message now appears before the user clicks the button as soon as they select a non MRI site for an MRI label. Once the error appears, the user can only select among the given MRI sites.

• Have you updated related documentation? yes

Testing instructions (if applicable)

1. Go to Candidate -> Access profile
2. Select a Candidate profile and click Create time point
3. Enter the details
4. Now there is a new error and the website does not allow you to select a non MRI site for an MRI visit label and the error appears before you click the "Create time point" button (as soon as you select the option). Now you get to select the new site with limited options only for MRI.

Link(s) to related issue(s)

• Resolves V26 S3 Support media #8923 (Reference the issue this fixes, if any.)