bcachefs: CONFIG_BCACHEFS_DEBUG_TRANSACTIONS no longer defaults to y

BCACHEFS_DEBUG_TRANSACTIONS is useful, but it's too expensive to have on
by default - and it hasn't been coming up in bug reports.

Turn it off by default until we figure out a way to make it cheaper.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/Kconfig

@@ -41,7 +41,6 @@ config BCACHEFS_POSIX_ACL
 config BCACHEFS_DEBUG_TRANSACTIONS
 	bool "bcachefs runtime info"
 	depends on BCACHEFS_FS
-	default y
 	help
 	This makes the list of running btree transactions available in debugfs.