refactor: exclude submittable doctype from SLA

[nextchamp-saqib]

Applying SLA on submittable doctypes doesn't work since status is not an editable field, hence excluding submittable doctypes from SLA's Apply On field

Other minor fixes:

• Fixed Customer Filter while fetching active SLAs
• SLA should be removed if no active SLA found

[codecov]

Codecov Report

Merging #29286 (cc88b31) into develop (82b2d22) will decrease coverage by 0.15%.
The diff coverage is 93.33%.

@@             Coverage Diff             @@
##           develop   #29286      +/-   ##
===========================================
- Coverage    57.96%   57.81%   -0.16%     
===========================================
  Files         1110     1110              
  Lines        68005    68019      +14     
===========================================
- Hits         39420    39322      -98     
- Misses       28585    28697     +112     

Impacted Files	Coverage Δ
...service_level_agreement/service_level_agreement.py	83.29% <93.33%> (+0.31%)	⬆️
...unts/report/purchase_register/purchase_register.py	34.24% <0.00%> (-39.05%)	⬇️
...wise_balance_history/batch_wise_balance_history.py	68.96% <0.00%> (-24.14%)	⬇️
...ext/accounts/report/balance_sheet/balance_sheet.py	36.36% <0.00%> (-21.82%)	⬇️
...e_purchase_register/item_wise_purchase_register.py	58.00% <0.00%> (-17.00%)	⬇️
...payroll/doctype/income_tax_slab/income_tax_slab.py	83.33% <0.00%> (-16.67%)	⬇️
...xt/stock/report/stock_analytics/stock_analytics.py	80.19% <0.00%> (-12.88%)	⬇️
...eport/item_variant_details/item_variant_details.py	84.33% <0.00%> (-3.62%)	⬇️
.../report/bom_operations_time/bom_operations_time.py	93.33% <0.00%> (-3.34%)	⬇️
...value/warehouse_wise_item_balance_age_and_value.py	92.40% <0.00%> (-2.54%)	⬇️
... and 20 more