GHA: Fix cirrus-cron scripts

Lack of proper testing possibility for github actions and lack of
script-testing by me, allowed several flaws through into 'main'.  Fix
the problems and manually test the scripts to make sure they're working.

Note: Also revert the stupid SHA-based action-pinning back to normal,
human-readable version numbers.  The value of using SHAs in the name of
improved "security" is real, but the value of human-readability and
ease of maintenance is greater.

Signed-off-by: Chris Evich <[email protected]>