Add (tentative) competitor count to delegate reports even if results not posted

[kr-matthews]

Now that #6628 is merged, results must be submitted (but not necessarily posted) when the delegate report is posted, so it should be possible to always include the competitor count, instead of leaving it out when results haven't been posted as is the current setup:

  <div>
    <strong>Competitors</strong>

    <% if competition.results_posted? %>
      <%= competition.competitors.count %>
    <% else %>
      Unknown, results are not posted yet.
    <% end %>
  </div>

Of course, the competitor count is not official/final and may change when results are posted, but as discussed in #720, this number is rarely off by more than 1 or 2:

However, I can confirm that the number of competitors matches for >= 95% of these results and devitations of more than 1-2 people are extremely rare.

Knowing the competitor count, even if it's off by a couple, helps put a competition into context. We could put a short note or symbol indicating that the number isn't final, or put it in parentheses, if results haven't been posted yet. (Both of these points taken from the linked discussion.)

If the tentative (pre-results-posted) competitor count can also be accessed via competition.competitors.count then this should be an easy change which I'd be happy to do myself.