diagnostics_channel: replace using with try-finally

[ayush23chaudhary]

Fixes: #64230

Description

This PR replaces instances of the experimental using syntax with try...finally blocks inside lib/diagnostics_channel.js.

Since Explicit Resource Management is still a flagged feature in V8, encountering using in core causes a segfault when running Node with the --no-js-explicit-resource-management flag. This refactor maintains the exact same resource cleanup semantics by manually calling [SymbolDispose]() in a finally block, avoiding the flagged syntax entirely.

Example of Refactor

Before:

using scope = this.withStoreScope(data);
return ReflectApply(fn, thisArg, args);

After

const scope = this.withStoreScope(data);
try {
  return ReflectApply(fn, thisArg, args);
} finally {
  scope[SymbolDispose]();
}

[Copilot]

Pull request overview

This PR removes the experimental using syntax from lib/diagnostics_channel.js, replacing it with equivalent try...finally disposal to avoid crashes when Node is run with --no-js-explicit-resource-management.

Changes:

• Replaced using statements with explicit try...finally blocks that invoke [SymbolDispose]().
• Updated scope handling in ActiveChannel, BoundedChannel, and TracingChannel paths to ensure disposal occurs reliably without relying on flagged syntax.

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[Renegade334]

DisposableStack is also a flagged global.

[ayush23chaudhary]

@Renegade334, I did not realize DisposableStack was part of the same flagged feature. I've replaced it with a standard array that manually iterates in reverse during disposal. Just pushed the update.