Removes the "arangojs instrumentation" code, which was a copy of the core
request processing classes of arangojs. The update to arangojs 10 would
have required major changes to these files, and they were a code quality
problem anyway.

Instead of our custom patches, we now rely on beforeRequest and
afterResponse. They can be specified once per Database, which is not
sufficient for our use case, so we currently call request() directly
instead of the proper executeTransaction(). Hopefully, arangojs will add
a way to specify these hooks in executeTransaction() as well. See
arangodb/arangojs#817 for the feature request.

BREAKING CHANGE: arangojs 8 is no longer supported. Update to arangojs 10.

BREAKING CHANGE: ArangoJSConfig is no longer exported. Import ConfigOptions
from arangojs/configuration directly if needed.