Relax assumptions about log file format

We only need to test, that the correct lines still contain the total
time and self time, the rest doesn't really matter.

We need to relax this, because while
77bd3e8 fixed the tests for vim, it
broke them for neovim, as that specific patch wasn't cherry-picked into
neovim yet.

Author: vimpostor

tests/test_general.vim

@@ -145,10 +145,10 @@ func Test_performance()
 	call assert_equal(printf("Called %d times", call_num), log[2])
 
 	let total_time = str2float(log[3]->matchstr('\d\.\d\+'))
-	call assert_equal(printf("Total time:   %.9f", total_time), log[3])
+	call assert_match("Total time:", log[3])
 
 	let self_time = str2float(log[4]->matchstr('\d\.\d\+'))
-	call assert_equal(printf(" Self time:   %.9f", self_time), log[4])
+	call assert_match("Self time:", log[4])
 
 	let individual_time = total_time / call_num
 	echo printf("Called %d times\nTotal time: %f\n Self time: %f\nIndividual time: %f", call_num, total_time, self_time, individual_time)