We regenerate TitleSuggest indices daily with UpdateSuggesterIndex.php. Sanity check and warn/reject/alert when there are large discrepencies between index size before promoting.

AC

• UpdateSuggesterIndex.php will refuse to promote if new index is <= 95% of raw size in bytes of prior day's index
• Separately, have an alert that fires if index is too old. This will catch both a failure to promote scenario but also other failure conditions (such as the index build just bombing out completely rather than an intentional automated decision to not promote)