Fix upgrade issues on ABCL and ECL
Fix upgrade on ABCL, that failed to properly process the fact that initialize-source-registry had moved from asdf/find-system to asdf/source-registry, yet was called in a cleanup function. Fix upgrade on ECL, that failed to correctly process that find-component was fmakunbound. It also seems to clear *central-registry* in some upgrade scenarios (that also moved from find-system to system-registry). Tweak script-support to not unconditionally frob-packages when ASDF isn't loaded yet, and to not include the asdf directory when loading and testing only UIOP.