fix: Never show AD col on drafts_for_ad.html

[jennifer-richards]

This should fix a transient HTML validation failure caused by assuming ad.name != doc.ad.plain_name() indicated that ad != doc.ad.

That check was, as far as I can tell, unnecessary because the search results were selected using doc.ad == ad. The check is removed here.

I'm leaving in the initial change from including ad_name to ad in the template context because I don't see a benefit to handing around the string instead of the full record.

For the record, the transient failure was:

======================================================================
FAIL: run_template_validation (ietf.utils.test_runner.TemplateValidationTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/__w/datatracker/datatracker/ietf/utils/test_runner.py", line 343, in run_template_validation
    self.validate_html.validate(self)
  File "/__w/datatracker/datatracker/ietf/utils/test_runner.py", line 1039, in validate
    testcase.fail('\n'.join(errors))
AssertionError: 
/tmp/html-validate-9azr981j/222fdd5170477301/ietf/templates/doc/drafts_for_ad.html:
     </td>      </tr>      
          ^^^^^^^^^^^
          info: A table row was 6 columns wide and exceeded the column count established by the first row (5).
Source snippet, lines 789 to 800:
789:                 <i class="bi bi-envelope"></i></a></span>
790:             
791:             <br>
792:             
793:         </td>
794:     
795: </tr>
796:         
797:     </tbody>
798: 
799: </table>
800: 

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (287cf0f) 88.80% compared to head (f5fd9ac) 88.80%.
Report is 3 commits behind head on main.

❗ Current head f5fd9ac differs from pull request most recent head 1bce192. Consider uploading reports for the commit 1bce192 to get more accurate results

Files	Patch %	Lines
ietf/utils/markup_txt.py	94.44%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6914      +/-   ##
==========================================
- Coverage   88.80%   88.80%   -0.01%     
==========================================
  Files         284      285       +1     
  Lines       40361    40377      +16     
==========================================
+ Hits        35843    35857      +14     
- Misses       4518     4520       +2     

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