We never call GetTraceRecordMode() on the TraceConfig produced in D8
but instead always create the default ring buffer.

That means we ignore the "record_mode" argument supplied in config json
file.

Given we never use this we can remove the parsing code. The same thing
is true for enable_systrace and enable_argument_filter. All of these
are never used in V8 (they were copied from Chrome) but are part of the
public API so this CL just removes our parsing code for them but leaves
them in the API for now.

Bug: v8:8339
Change-Id: Iab5169536e20c19a784a55d013765125dd701773
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1698397Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62704}