[ticket/12697] Delete cached extension schema.json files after testing

PHPBB3-12697
Merge pull request #2580 from VSEphpbb/ticket/12697

[ticket/12697] Delete cached extension schema.json files after testing

* VSEphpbb/ticket/12697:
  [ticket/12697] Delete cached extension schema.json files after testing
[ticket/12687] Wrap $GLOBALS['starttime'] in a if

PHPBB3-12687
[ticket/12687] Don't check if memory_get_peak_usage() exists

PHPBB3-12687
[ticket/12687] Display the number of cached queries

PHPBB3-12687
[ticket/12687] Remove french spaces

PHPBB3-12687
Merge pull request #2570 from Nicofuma/ticket/12687

[ticket/12687] Add a constant to display the load time without DEBUG

* Nicofuma/ticket/12687:
  [ticket/12687] Remove french spaces
  [ticket/12687] Display the number of cached queries
  [ticket/12687] Don't check if memory_get_peak_usage() exists
  [ticket/12687] Wrap $GLOBALS['starttime'] in a if
  [ticket/12687] Fix the namespace of $request
  [ticket/12687] Update doc block
  [ticket/12687] Use microtime(true)
  [ticket/12687] Remove globals
  [ticket/12687] Return a string and move the displaying of the sql report
  [ticket/12687] Rename DISPLAY_LOAD_TIME to PHPBB_DISPLAY_LOAD_TIME
  [ticket/12687] Display the explain link only when DEBUG is set
  [ticket/12687] Add a constant to display the load time without DEBUG