allow to trace with lazy text calculation

[ygalbel]

In internal-channel.ts file there is a trace after channel is constructed.
In this trace, the full stacktrace is added.

The trace is written only when the log level is on trace, but the stacktrace is calculated in any case.
We found in our usage, that if you have a big bundle file it can take few seconds to calculate the stacktrace, it can be reasonable in trace mode but not in production.

I suggest to made the text in trace function to allow also a delegate that returns a function.
The delegate will be called only when the trace is materialized.

[linux-foundation-easycla]

• ✅login: ygalbel / (6cb0015)

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[murgatroid99]

Simpler solution: surround that call to trace with if (isTracerEnabled('channel_stacktrace')) { ... }. This is how we are handling other cases where producing the trace log text is expensive.

Even simpler solution: just delete that trace log line. I don't think it's actually that valuable.

Either way, I recommend rebasing the change onto the @grpc/[email protected] branch to get the change out faster.