Fix too eager dispose in js block tracing

[LukaszRozmej]

Changes

• Makes engine dispose lazy on serialization, fixing the issue it was disposed too eagerly introduced in Javascript Tracer resource leak #6929
• Disposes engines on exception
• Removes ArrayPool as it is hard to dispose it just in the right time

Types of changes

What types of changes does your code introduce?

• Bugfix (a non-breaking change that fixes an issue)
• New feature (a non-breaking change that adds functionality)
• Breaking change (a change that causes existing functionality not to work as expected)
• Optimization
• Refactoring
• Documentation update
• Build-related changes
• Other: Description

Testing

Requires testing

• Yes
• No

If yes, did you write tests?

• Yes
• No

Notes on testing

@natebeauregard can you test it?

[natebeauregard]

@LukaszRozmej Changes look good, I'll test this later today while gathering the performance numbers to ensure that everything is working ok and will approve then

[natebeauregard]

Testing looked good, all of the JS tracers can be executed from the JSON-RPC endpoint. LGTM