tests: simplify by dropping unnecessary for loops

Rather than manually looping over a set of items and plugging those
items into a template string which is printed repeatedly, achieve the
same effect by taking advantage of `printf` which loops over its
arguments automatically.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t7110-reset-merge.sh

@@ -8,7 +8,7 @@ test_description='Tests for "git reset" with "--merge" and "--keep" options'
 . ./test-lib.sh
 
 test_expect_success setup '
-    for i in 1 2 3; do echo line $i; done >file1 &&
+    printf "line %d\n" 1 2 3 >file1 &&
     cat file1 >file2 &&
     git add file1 file2 &&
     test_tick &&