Improve ruleset for generating project hashtags

Summary:
Ref T9551. We currently use the same logic for generating project hashtags and Phriction slugs, but should be a little more conservative with project hashtags.

Stop them from generating with stuff that won't parse in a "Reviewers:" field or generally in commments (commas, colons, etc).

Test Plan:
Created a bunch of projects with nonsense in them and saw them generate pretty reasonable hashtags.

{F873456}

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T9551

Differential Revision: https://secure.phabricator.com/D14261

src/applications/project/query/PhabricatorProjectQuery.php

@@ -7,7 +7,6 @@ final class PhabricatorProjectQuery
   private $phids;
   private $memberPHIDs;
   private $slugs;
-  private $phrictionSlugs;
   private $names;
   private $nameTokens;
   private $icons;
@@ -50,11 +49,6 @@ final class PhabricatorProjectQuery
     return $this;
   }
 
-  public function withPhrictionSlugs(array $slugs) {
-    $this->phrictionSlugs = $slugs;
-    return $this;
-  }
-
   public function withNames(array $names) {
     $this->names = $names;
     return $this;
@@ -308,13 +302,6 @@ final class PhabricatorProjectQuery
         $this->slugs);
     }
 
-    if ($this->phrictionSlugs !== null) {
-      $where[] = qsprintf(
-        $conn,
-        'phrictionSlug IN (%Ls)',
-        $this->phrictionSlugs);
-    }
-
     if ($this->names !== null) {
       $where[] = qsprintf(
         $conn,