Fix symbolicName computation for customer trials

Steps to reproduce:

1. Authenticate against https://nos-preprod-connect.nuxeocloud.com/ as a regular customer, for example bchauvin-test-user-1
2. Navigate to https://nos-preprod-connect.nuxeocloud.com/nuxeo/site/connect/applications
3. Under AAAA - Cloud, push the button "Create new trial Studio Project"
4. In "Project Name" field, use "INS2-MetropolitanLifeInsurance"
5. Observe that the project is correctly created and the symbolic name is ins2
6. Go back to https://nos-preprod-connect.nuxeocloud.com/nuxeo/site/connect/applications and push the button "Create new trial Studio Project" under AAAA - Cloud
7. In "Project Name" field, use "INS2-CampaignLifeInsurance" which is different from step
8. Observe that an error message is displayed

    Some errors prevented from processing your form : Project name can only contain alphanumeric characters. 

   This is due to the fact that the computed symbolic name is the same as for the first trial