fix: total leaves allocated not validated and recalculated on updates post submission

[ruchamahabal]

Problem

In Leave Allocation, if New Leaves Allocated field is updated via Data Import or API, Total Leaves Allocated is not recalculated on the server-side post submission. Moreover, the following validations don't run if someone updates allocation after submission:

• validate_back_dated_allocation: To check if the allocation that is being updated is already carried forward to a future allocation
• validate_total_leaves_allocated: To check if the total leaves allocated are more than the days in the period, eg: should not allow 30 leaves being allocated for 15 days
• validate_leave_allocation_days: To check if the total leaves allocated do not exceed max_leaves_allowed within the leave period setup in Leave Type

Fix

• Recalculate Total Leaves Allocated on server-side
• Run the above stated validations on on_update_after_submit
• Add tests for these validations and total calculations for updates done before and after submission

[codecov]

Codecov Report

Merging #30569 (793164a) into develop (e8118fc) will increase coverage by 19.40%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##           develop   #30569       +/-   ##
============================================
+ Coverage    41.63%   61.03%   +19.40%     
============================================
  Files         1083     1083               
  Lines        69141    69145        +4     
============================================
+ Hits         28786    42205    +13419     
+ Misses       40355    26940    -13415     

Impacted Files	Coverage Δ
...xt/hr/doctype/leave_allocation/leave_allocation.py	97.27% <100.00%> (+24.86%)	⬆️
.../report/bom_operations_time/bom_operations_time.py	89.13% <0.00%> (-2.18%)	⬇️
erpnext/stock/valuation.py	96.69% <0.00%> (-0.11%)	⬇️
erpnext/regional/india/e_invoice/utils.py	42.52% <0.00%> (ø)
erpnext/stock/doctype/pick_list/pick_list.py	72.09% <0.00%> (ø)
erpnext/stock/report/bom_search/bom_search.py	0.00% <0.00%> (ø)
...ccounts/doctype/mode_of_payment/mode_of_payment.py	72.00% <0.00%> (ø)
...e/course_scheduling_tool/course_scheduling_tool.py	0.00% <0.00%> (ø)
...production_plan_summary/production_plan_summary.py	0.00% <0.00%> (ø)
..._time_for_issues/first_response_time_for_issues.py	0.00% <0.00%> (ø)
... and 372 more