Ensure Logs Are Captured for Assertions and Printed During Tests (#7769)

This PR enhances **`test_log_capture`**, ensuring logs are **captured
for assertions** and **printed to the console** during test execution.

## **Motivation**  

- Partially addresses #6119 and #6125, to improves developer **tracing
and debugging** in XCM-related tests.
- Builds on #7594, improving **log visibility** while maintaining test
**log capture capabilities**.
- While writing tests for #7234, I noticed this function was missing.
This PR adds it to streamline log handling in unit tests.

## **Changes**  

- Ensures logs up to `TRACE` level are **captured** (for assertions) and
**printed** (for visibility).
- Refines documentation to clearly specify **when to use** each
function.
- **Removes ANSI escape codes** from captured logs to ensure clean,
readable assertions.

## **When to Use?**  

| Usage | Captures Logs? | Prints Logs? | Example |

|----------------------------------------------|-----------------|--------------|-----------------------------------------------|
| `init_log_capture(LevelFilter::INFO, false)` |  Yes |  No | Capture
logs for assertions without printing. |
| `init_log_capture(LevelFilter::TRACE, true)` |  Yes |  Yes | Capture
logs and print them in test output. |
| `sp_tracing::init_for_tests()` |  No | 

 Yes | Print logs to the
console without capturing. |

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Co-authored-by: cmd[bot] <41898282+github-actions[bot]@users.noreply.github.com>