Fix fetch_info clear parameter type validation (#6756)

[harshitgupta62]

Summary

Fixes an issue where the clear parameter in the fetch_info RPC method accepts non-boolean values due to loose type coercion.

Problem

The current implementation uses asBool() directly, which coerces non-boolean JSON values into boolean. This leads to unintended behavior where inputs like:

• { "clear": "false" }
• { "clear": [1] }
• { "clear": {} }

are treated as true, causing clearLedgerFetch() to be triggered unexpectedly.

Solution

Added strict type validation using isBool() before calling asBool(). Now, only an explicit boolean true value will trigger the clearing of ledger fetch state.

Behavior After Fix

• { "clear": true } → clears fetch state
• { "clear": false } → does not clear
• Non-boolean values → ignored (no unintended clearing)

Impact

• Prevents unintended clearing of ledger fetch state
• Maintains backward compatibility (no breaking changes)

Related Issue

Closes #6756