test: check for ASAN properly (#24224)

Follow-up to #24195.

test/functional/legacy/memory_usage_spec.lua

@@ -13,7 +13,7 @@ local is_os = helpers.is_os
 local is_ci = helpers.is_ci
 
 local function isasan()
-  local version = eval('execute("version")')
+  local version = eval('execute("verbose version")')
   return version:match('-fsanitize=[a-z,]*address')
 end
 

test/old/testdir/check.vim

@@ -168,7 +168,7 @@ endfunc
 " Command to check for not running under ASAN
 command CheckNotAsan call CheckNotAsan()
 func CheckNotAsan()
-  if execute('version') =~# '-fsanitize=[a-z,]*\<address\>'
+  if execute('verbose version') =~# '-fsanitize=[a-z,]*\<address\>'
     throw 'Skipped: does not work with ASAN'
   endif
 endfunc