Fix the following issues in the test suite:
- lack of quoting for variables
- declare function variables local when missing (prevent accidental
overwrite of global variables)
- for variables with underscore in the name use plain "$VAR_NAME"
instead of { } (unless necessary)
- minor style adjustments like moving quotes to the end of the same
string
Signed-off-by: David Sterba <dsterba@suse.com>