chore: added status table cleanup logic before backup with code refactor

[saurav-malani]

Description

1. Refactored backup DS logic to reduce code complexity & improve readability.
2. added logic to clean-up backup status table to delete status corresponding to attempt older than last 2.

Notion Ticket

https://www.notion.so/rudderstacks/backup-refactor-Delete-stale-job-statuses-before-backing-up-946496e6688749b790122d20e6c93c7d

[codecov]

Codecov Report

Base: 44.00% // Head: 43.99% // Decreases project coverage by -0.00% ⚠️

Coverage data is based on head (1309e30) compared to base (09dba21).
Patch coverage: 74.95% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2542      +/-   ##
==========================================
- Coverage   44.00%   43.99%   -0.01%     
==========================================
  Files         187      188       +1     
  Lines       39086    39203     +117     
==========================================
+ Hits        17198    17248      +50     
- Misses      20807    20850      +43     
- Partials     1081     1105      +24     

Impacted Files	Coverage Δ
jobsdb/backup.go	74.90% <74.90%> (ø)
jobsdb/jobsdb.go	65.44% <100.00%> (-2.63%)	⬇️
warehouse/schema.go	47.82% <0.00%> (-1.16%)	⬇️
enterprise/reporting/reporting.go	9.77% <0.00%> (+1.43%)	⬆️
enterprise/reporting/setup.go	52.38% <0.00%> (+14.28%)	⬆️

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[atzoum]

thank you @saurav-malani!