Don't assume current l10n cache files are .cdb
We already copy '*' from the temporary build directory into the real l10n cache
directory, so we can (non-recursively) glob '*' for files to copy into the
temporary build directory as well.
By the same logic, exclude '*' in cache/l10n rather than '*.cdb'.
Task: T105683
Change-Id: Ib976cd5bfb12fc0842ca3fd4745f59bf5f5d9fd3