Fix cleanup of packages backup directory when using install-packages.sh

The install-packages.sh script cleans up some directories after install:

echo "Clean up package installation directories: $backupDir, $tmpDir"
rm -rf $backupDir
rm -rf $tmpDir
 

The backup directory is needed to re-perform installs in cases where the same bundles are held by multiple packages.

This is especially useful when working with hotfix packages: typically, when using a 10.10-HF version (on a custom repository where the install-packages.sh script was backported), installing the jsf-ui package ends up with an incomplete list of bundles in the nxserver/bundles directory (see details below).

Commenting out the "rm -rf $backupDir" in the install-packages.sh script fixes the issue.