ci: postgres unittests configurations

[c-p-b]

This PR simply enables running of postgres tests without doing anything else. It requires a couple of minor commits in Frappe repository: https://github.com/cpdeethree/frappe/tree/enable-postgres-tests

These commits are also included on the larger frappe and erpnext pr's with changes for postgres support for ERPNext:

#28359

Thus (minus the DEBUG branch pointer commit), all changes here are strict subsets of the above PR's

Depends on: frappe/frappe#15354

[ankush]

This is technically ready for review but can't be merged till frappe/frappe#15354 is merged, hence marking it draft for now.

Also I need to make this CI workflow conditional for postgres PRs.

[codecov]

Codecov Report

Merging #28952 (d864972) into develop (ebc1039) will increase coverage by 5.99%.
The diff coverage is 100.00%.

❗ Current head d864972 differs from pull request most recent head 3871af2. Consider uploading reports for the commit 3871af2 to get more accurate results

@@             Coverage Diff             @@
##           develop   #28952      +/-   ##
===========================================
+ Coverage    49.69%   55.68%   +5.99%     
===========================================
  Files         1131     1131              
  Lines        67513    67516       +3     
===========================================
+ Hits         33548    37597    +4049     
+ Misses       33965    29919    -4046     

Impacted Files	Coverage Δ
erpnext/regional/india/setup.py	95.36% <100.00%> (+0.07%)	⬆️
erpnext/utilities/product.py	14.70% <0.00%> (-35.30%)	⬇️
erpnext/shopping_cart/product_info.py	30.30% <0.00%> (-21.22%)	⬇️
...eport/item_variant_details/item_variant_details.py	84.33% <0.00%> (-3.62%)	⬇️
erpnext/education/doctype/student/student.py	73.68% <0.00%> (-3.16%)	⬇️
...ion/doctype/course_enrollment/course_enrollment.py	44.00% <0.00%> (-2.00%)	⬇️
...xt/stock/report/stock_analytics/stock_analytics.py	91.08% <0.00%> (-1.99%)	⬇️
...e/shopping_cart_settings/shopping_cart_settings.py	65.38% <0.00%> (-1.93%)	⬇️
...wise_balance_history/batch_wise_balance_history.py	91.37% <0.00%> (-1.73%)	⬇️
erpnext/shopping_cart/product_query.py	61.19% <0.00%> (-1.50%)	⬇️
... and 170 more

[ankush]

note: Reverted change to HSN code creation since it appears that something else is rolling back full transaction as apparent from CI run on this commit: d864972

https://github.com/frappe/erpnext/runs/4684613490?check_suite_focus=true

This is the root cause behind HSN codes not getting created properly in tests. I can fix this here but feels like this needs to be handled better by the framework. Improper error handling is causing rollback. Well, actually both changes are required, this kinda error handling in regional setup will cause weird state in DB.

erpnext/erpnext/regional/india/setup.py

Lines 715 to 723 in d864972

	for d in docs:
	try:
	doc = frappe.get_doc(d)
	doc.flags.ignore_permissions = True
	doc.insert()
	except frappe.NameError:
	frappe.clear_messages()
	except frappe.DuplicateEntryError:
	frappe.clear_messages()

cc: @gavindsouza @deepeshgarg007

for postgres DB we are just rolling back everything on SQL exception 😐

https://github.com/frappe/frappe/blob/96e1b7dcf9d39651aa72ea7af151aa15208e765b/frappe/database/database.py#L165-L166

[ankush]

Merging just the CI change for now, rest will require a fix at framework level.