Bug: Default value for `forex_enabled` if config is not set



Currently, if the `forex_enabled` flag is not present as an ENV, it is leading to deserialization errors.
Need to modify it in such a way to assume the default value (false) if the ENV is not present.
diff --git a/crates/analytics/src/lib.rs b/crates/analytics/src/lib.rs
index 89f5cbd5b9c..2cd2da30e45 100644
--- a/crates/analytics/src/lib.rs
+++ b/crates/analytics/src/lib.rs
@@ -1010,25 +1010,28 @@ impl AnalyticsProvider {
 }
 
 #[derive(Clone, Debug, serde::Deserialize)]
-#[serde(tag = "source")]
-#[serde(rename_all = "lowercase")]
+#[serde(tag = "source", rename_all = "lowercase")]
 pub enum AnalyticsConfig {
     Sqlx {
         sqlx: Database,
+        #[serde(default)]
         forex_enabled: bool,
     },
     Clickhouse {
         clickhouse: ClickhouseConfig,
+        #[serde(default)]
         forex_enabled: bool,
     },
     CombinedCkh {
         sqlx: Database,
         clickhouse: ClickhouseConfig,
+        #[serde(default)]
         forex_enabled: bool,
     },
     CombinedSqlx {
         sqlx: Database,
         clickhouse: ClickhouseConfig,
+        #[serde(default)]
         forex_enabled: bool,
     },
 }

## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [x] Bugfix
- [ ] New feature
- [ ] Enhancement
- [x] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->
Currently, if the `forex_enabled` feature flag is not present as an ENV, it is leading to deserialization errors.
Modified it in such a way to assume the default value (false) if the ENV is not present.

### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

<!--
Provide links to the files with corresponding changes.

Following are the paths where you can find config files:
1. `config`
2. `crates/router/src/configs`
3. `loadtest/config`
-->


## Motivation and Context
<!--
Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.

If you don't have an issue, we'd recommend starting with one first so the PR
can focus on the implementation (unless it is an obvious bug or documentation fix
that will have little conversation).
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Fix deserialization errors for analytics

## How did you test it?
<!--
Did you write an integration/unit/API test to verify the code changes?
Or did you test this change manually (provide relevant screenshots)?
-->
Removed the `forex_enabled` feature flag from local envs, and replicated the error
<img width="806" alt="Screenshot 2025-04-02 at 2 34 43 PM" src="https://github.com/user-attachments/assets/b275cc79-1fad-4ee7-81a5-acaf780e771c" />

Need to remove the env `forex_enabled` during deployment, and then test out the analytics section..
Tested on local, by removing the `forex_enabled` env and checking the analytics API calls, worked as expected
<img width="638" alt="image" src="https://github.com/user-attachments/assets/56ba5d51-ff1c-4d42-8401-ea00e7bc6d22" />

Curl: 
```bash
curl --location 'http://localhost:8080/analytics/v1/org/metrics/payments' \
--header 'Accept: */*' \
--header 'Accept-Language: en-US,en;q=0.9' \
--header 'Connection: keep-alive' \
--header 'Content-Type: application/json' \
--header 'Origin: http://localhost:9000' \
--header 'Referer: http://localhost:9000/' \
--header 'Sec-Fetch-Dest: empty' \
--header 'Sec-Fetch-Mode: cors' \
--header 'Sec-Fetch-Site: same-site' \
--header 'User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36' \
--header 'api-key: hyperswitch' \
--header 'authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ1c2VyX2lkIjoiM2RlMDFhYWYtOWVkMi00YTY5LTg3YWItNWU1YmI2ZWFiNGQ5IiwibWVyY2hhbnRfaWQiOiJtZXJjaGFudF8xNzQyMjEyMzQxIiwicm9sZV9pZCI6Im9yZ19hZG1pbiIsImV4cCI6MTc0Mjk4MDgyOCwib3JnX2lkIjoib3JnX3pMQmRNTnpLaDZrNmhiT2tockdJIiwicHJvZmlsZV9pZCI6InByb19LWnhHZ21rUHFkMldQdXBFa2psWCIsInRlbmFudF9pZCI6InB1YmxpYyJ9.aD185AZEOcIjHnLnZZ9GJ2ujSHIdRPbPtrYhzNo0V4M' \
--header 'sec-ch-ua: "Chromium";v="128", "Not;A=Brand";v="24", "Google Chrome";v="128"' \
--header 'sec-ch-ua-mobile: ?0' \
--header 'sec-ch-ua-platform: "macOS"' \
--data '[
    {
        "timeRange": {
            "startTime": "2025-03-01T18:30:00Z",
            "endTime": "2025-03-31T09:22:00Z"
        },
        "source": "BATCH",
        "metrics": [
            "payment_processed_amount"   
        ],
        "timeSeries": {
            "granularity": "G_ONEDAY"
        },
        "delta": true
    }
]'
```

## 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
