Update sig-repo.synopsys references to repo.blackduck.com in previously created Dockerfiles

[niravrsynopsys]

This change can be merged before releasing 9.10.1 and 8.11.2.

Updates are as follows:

• Only replaced the artifactory hostname references from sig-repo.synopsys.com to repo.blackduck.com for previously created Dockerfiles. Previous jar names and repo names are the same. The corresponding Docker images are already published on Docker Hub. This update just ensures that in case these images are ever manually built again, the docker build would succeed even after sig-repo.synopsys.com ceases to exist.
• Updated README.md

JIRA

IDETECT-4483