Issue:
Bug: Create indexes for tracker tables in v2_compatible_migrations





Pull request description:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [x] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->
Since `id` column is introduced as varchar for a few major tracker tables in v2, index creation was missed in v2_compatible_migrations directory. This PR includes that.


### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

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2. `crates/router/src/configs`
3. `loadtest/config`
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## Motivation and Context
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If it fixes an open issue, please link to the issue here.

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To improve DB query time.


## How did you test it?
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Did you write an integration/unit/API test to verify the code changes?
Or did you test this change manually (provide relevant screenshots)?
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Ran diesel migrations


## Checklist
<!-- Put an `x` in the boxes that apply -->

- [x] I formatted the code `cargo +nightly fmt --all`
- [x] I addressed lints thrown by `cargo clippy`
- [x] I reviewed the submitted code
- [ ] I added unit tests for my changes where possible


Testing:

Ran diesel migrations

Patch:
diff --git a/v2_compatible_migrations/2025-10-07-131000_add_indexes_on_id_columns/down.sql b/v2_compatible_migrations/2025-10-07-131000_add_indexes_on_id_columns/down.sql
new file mode 100644
index 00000000000..fb18e635e20
--- /dev/null
+++ b/v2_compatible_migrations/2025-10-07-131000_add_indexes_on_id_columns/down.sql
@@ -0,0 +1,22 @@
+-- Drop unique indexes on id columns
+-- This will remove the unique indexes created for id column performance optimization and data integrity
+
+-- tracker tables
+DROP INDEX IF EXISTS customers_id_index;
+
+DROP INDEX IF EXISTS payment_intent_id_index;
+
+DROP INDEX IF EXISTS payment_attempt_id_index;
+
+DROP INDEX IF EXISTS payment_methods_id_index;
+
+DROP INDEX IF EXISTS refund_id_index;
+
+-- Accounts tables
+DROP INDEX IF EXISTS business_profile_id_index;
+
+DROP INDEX IF EXISTS merchant_account_id_index;
+
+DROP INDEX IF EXISTS merchant_connector_account_id_index;
+
+DROP INDEX IF EXISTS organization_id_index;
diff --git a/v2_compatible_migrations/2025-10-07-131000_add_indexes_on_id_columns/up.sql b/v2_compatible_migrations/2025-10-07-131000_add_indexes_on_id_columns/up.sql
new file mode 100644
index 00000000000..a8e27af1485
--- /dev/null
+++ b/v2_compatible_migrations/2025-10-07-131000_add_indexes_on_id_columns/up.sql
@@ -0,0 +1,21 @@
+-- Create unique indexes on id columns for better query performance and data integrity
+
+-- Tracker Tables
+CREATE UNIQUE INDEX IF NOT EXISTS customers_id_index ON customers (id);
+
+CREATE UNIQUE INDEX IF NOT EXISTS payment_intent_id_index ON payment_intent (id);
+
+CREATE UNIQUE INDEX IF NOT EXISTS payment_attempt_id_index ON payment_attempt (id);
+
+CREATE UNIQUE INDEX IF NOT EXISTS payment_methods_id_index ON payment_methods (id);
+
+CREATE UNIQUE INDEX IF NOT EXISTS refund_id_index ON refund (id);
+
+-- Accounts Tables
+CREATE UNIQUE INDEX IF NOT EXISTS business_profile_id_index ON business_profile (id);
+
+CREATE UNIQUE INDEX IF NOT EXISTS merchant_account_id_index ON merchant_account (id);
+
+CREATE UNIQUE INDEX IF NOT EXISTS merchant_connector_account_id_index ON merchant_connector_account (id);
+
+CREATE UNIQUE INDEX IF NOT EXISTS organization_id_index ON organization (id);