User received unclear and confusing message if he/she tried to take backup and has incompatible service to util versions.
Steps to Reproduce:
#1 have incompatible util / service versions installed on PMM-CLIENT
#2 take a backup on backup inventory page
You received unclear message which is very general (503 internal server error)
User should received specific information why they cannot take a backup f.e "you have incompatible version of xtrabackup 2.4 required version is 8.0 Please update xtrabackup.
Currently, there are couple of situations where the service could be incompatible for backup or restore:
(1) needed software is not installed on the service
(2) backup software tools should be the same version
(3) backup tools are not compatible with the database version
(4) target MySQL version is not compatible with backup
For each such case introduce a new error code that can be used on the FE side to show to the user appropriate instruction on how to resolve the issue e.g. in case of (1), (2) - just show the link to the instruction for installing (reinstalling) xtrabackup.