Convert doDeleteArticleReal to startAtomic()/endAtomic()

Convert doDeleteArticleReal to startAtomic()/endAtomic()

* They no longer commit the update, but just make sure
  it is part of a transaction. The BEGIN/COMMIT will
  happen at request start/end given DBO_TRX or in this
  method otherwise (like when in CLI mode). This avoids
  premature committing of other transactions.
* FileDeleteForm was the only caller using $commit=false
  for WikiPage::doDeleteArticleReal() and its proxies
  WikiPage::doDeleteArticle() and Article::doDeleteArticle().
  The ugly $commit flag is now removed.
* No caller was using $id for WikiPage::doDeleteArticleReal()
  and its proxies WikiPage::doDeleteArticle() and
  Article::doDeleteArticle(). It is now removed and we can
  be sure the lock() and CAS logic always hit in the method.
  The rollback() calls are not needed given the page row lock
  and having them there could break outer transactions.
* Updated FileDeleteForm to use startAtomic()/endAtomic() so
  the article and file delete are still wrapped in a
  transaction. Note that LocalFile::delete() does reference
  counting and trxLevel() checks so it will not try to begin()
  and break FileDeleteForm's transaction via startAtomic().
* Moved less important 'page-recent-delete' key update down
  for sanity in case it blows up.

Change-Id: Idb98510506c0edd02236c30badaec97d86e07696