Use AsyncBackup to create the backups

[burmanm]

What this PR does:
During reconcile, use BackupStatus to check the Status of the Backup and move on only once it has been completed on every node.

This also ensures the backup completion is correctly logged in the objects, even if timeout occurs during the status callbacks or the operator restarts.

Which issue(s) this PR fixes:
Fixes #633

Checklist

• Changes manually tested
• Automated Tests added/updated
• Documentation added/updated
• CHANGELOG.md updated (not required for documentation PRs)
• CLA Signed: DataStax CLA

[sonarqubecloud]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
5.7% Duplication

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[codecov]

Codecov Report

Merging #1049 (ff05b2d) into main (8614857) will decrease coverage by 0.15%.
The diff coverage is 33.75%.

@@            Coverage Diff             @@
##             main    #1049      +/-   ##
==========================================
- Coverage   57.43%   57.28%   -0.15%     
==========================================
  Files         100      100              
  Lines       10045    10066      +21     
==========================================
- Hits         5769     5766       -3     
- Misses       3783     3798      +15     
- Partials      493      502       +9     

Files Changed	Coverage Δ
pkg/medusa/grpc.go	0.00% <0.00%> (ø)
pkg/medusa/medusa.pb.go	3.14% <ø> (ø)
pkg/medusa/medusa_grpc.pb.go	0.00% <0.00%> (ø)
controllers/medusa/medusabackupjob_controller.go	52.10% <45.00%> (-6.04%)	⬇️

... and 3 files with indirect coverage changes