Database: Generalise SQL before writing to debug log

The log often contains stuff like the following, where the trimmed
snippet can span many many lines:

* DatabaseBase::query: Writes done: INSERT IGNORE INTO `msg_resource`
   (mr_lang,mr_resource,mr_blob,mr_timestamp) VALUES ('۶?2x?ptt?`0<snip>?`0??O?')
* DatabaseBase::query: Writes done: REPLACE INTO `objectcache`
   (keyname,value,exptime) VALUES ('۶?2x?ptt?`0<snip>?`0??O ?`???`0??O ?`???`0?')

Bug: 67382
Change-Id: I76ca042f166fed56d86df15f788702384d48064c
Merge "Database: Generalise SQL before writing to debug log"