Convert2RHEL fails with "Error: Error writing to file /var/cache/yum/x86_64/7Server/rhel-7-server-els-rpms/gen/primary_db.sqlite: [Errno 28] No space left on device"

Issue

Convert2RHEL utility fails to download RHEL 7 package metadata with the below error.

========== Error (Must fix before conversion) ==========
(ERROR) ENSURE_KERNEL_MODULES_COMPATIBILITY::PROBLEM_WITH_PACKAGE_REPO - Could not download package metadata
     Description: There was an error retrieving the package metadata to verify kernel modules are available in RHEL.
     Diagnosis: We were unable to download the repository metadata for (rhel-7-server-els-rpms) to determine packages containing kernel modules.  Can be caused by not
enough disk space in /var/cache or too little memory.  The yum output below may have a clue for what went wrong in this case:

    Loaded plugins: fastestmirror, product-id, ps, search-disabled-repos,
                  : subscription-manager
    Loading mirror speeds from cached hostfile
    Error: Error writing to file /var/cache/yum/x86_64/7Server/rhel-7-server-els-rpms/gen/primary_db.sqlite: [Errno 28] No space left on device