Bug Fix for Cannot install version 1.3: DDLM package not found

[ssparach]

Issue Description:
There is an issue with the installation of DDLM packages, specifically when a newer installer version (e.g., 1.6.1) is run before an older version (e.g., 1.5.7). This sequence causes the DDLM packages to not install for the older version, resulting in a "package not found" error during provisioning.

Root Cause:
Processing the DDLM package enters a conditional statement due to the stale value for GetExistingPackageIfHigherVersion (set because the singleton packages have already been processed). Consequently, the singleton package is merely re-registered, and the DDLM package is not added when older versions are executed.

Fix:
Once the higher version package has been re-registered or its status is confirmed to be okay, the value for m_existingPackageIfHigherVersion should be cleared.

Testing:
Built both a new and an older version of the installer with the fix. First ran the new version, followed by the older one, ensuring that only a single Singleton package was present. Verified that the DDLM packages, main package, and frameworks installed corresponded to each installer version.

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