t1005: modernize "! test -f" to "test_path_is_missing"

Replace instances of "! test -f <file>" with "test_path_is_missing <file>".
This macro provides better diagnostics when the test fails (it prints
"Path exists:" instead of silently failing).

Signed-off-by: Tian Yuchen <a3205153416@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: malon7782

t/t1005-read-tree-reset.sh

@@ -40,7 +40,7 @@ test_expect_success 'reset should remove remnants from a failed merge' '
 	git ls-files -s &&
 	read_tree_u_must_succeed --reset -u HEAD &&
 	git ls-files -s >actual &&
-	! test -f old &&
+	test_path_is_missing old &&
 	test_cmp expect actual
 '
 
@@ -56,7 +56,7 @@ test_expect_success 'two-way reset should remove remnants too' '
 	git ls-files -s &&
 	read_tree_u_must_succeed --reset -u HEAD HEAD &&
 	git ls-files -s >actual &&
-	! test -f old &&
+	test_path_is_missing old &&
 	test_cmp expect actual
 '
 
@@ -72,7 +72,7 @@ test_expect_success 'Porcelain reset should remove remnants too' '
 	git ls-files -s &&
 	git reset --hard &&
 	git ls-files -s >actual &&
-	! test -f old &&
+	test_path_is_missing old &&
 	test_cmp expect actual
 '
 
@@ -88,7 +88,7 @@ test_expect_success 'Porcelain checkout -f should remove remnants too' '
 	git ls-files -s &&
 	git checkout -f &&
 	git ls-files -s >actual &&
-	! test -f old &&
+	test_path_is_missing old &&
 	test_cmp expect actual
 '
 
@@ -104,7 +104,7 @@ test_expect_success 'Porcelain checkout -f HEAD should remove remnants too' '
 	git ls-files -s &&
 	git checkout -f HEAD &&
 	git ls-files -s >actual &&
-	! test -f old &&
+	test_path_is_missing old &&
 	test_cmp expect actual
 '