This patch will disable meta index by default until the deadlock issues
are resolved.

Change-Id: I41a05045e6fb9c1e71a5db2fe2d78619d5f190a6
Signed-off-by: Gayan Perera <gayanper@gmail.com>
Reviewed-on: https://git.eclipse.org/r/c/jdt/eclipse.jdt.core/+/181874
Tested-by: JDT Bot <jdt-bot@eclipse.org>
Reviewed-by: Andrey Loskutov <loskutov@gmx.de>