reporter-rhtsupport: skip hints check if uploaded data is really large

Hints check uploads the entire problem directory tarball.
If the tarball is hundreds of megabytes, that is not a good idea.

Perhaps "hints" thing on the server one day will be changed so that
it accepts a truncated set of data.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>