test/system: Simplify the line count checks by relying on Bats >= 1.7.0

Fedora 35 was stuck with Bats 1.5.0.  However, it reached End of Life on
13th December 2022 and was dropped from the CI [1].  Fedora 36 is the
oldest supported Fedora and it has Bats 1.8.2.

Therefore, there's no need to retain compatibility with Bats < 1.7.0.

Note that bats_require_minimum_version itself is only available from
Bats 1.7.0 [2].

[1] Commit 419e4e8
    containers#1237

[2] Bats commit 71d6b71cebc3d32b
    bats-core/bats-core#556
    https://bats-core.readthedocs.io/en/stable/warnings/BW02.html

containers#1273

test/system/102-list.bats

@@ -20,6 +20,7 @@ load 'libs/bats-assert/load'
 load 'libs/helpers'
 
 setup() {
+  bats_require_minimum_version 1.7.0
   _setup_environment
   cleanup_all
 }
@@ -71,9 +72,7 @@ teardown() {
   assert_success
   assert_line --index 1 --partial "<none>"
   assert [ ${#lines[@]} -eq 3 ]
-  if check_bats_version 1.7.0; then
-    assert [ ${#stderr_lines[@]} -eq 0 ]
-  fi
+  assert [ ${#stderr_lines[@]} -eq 0 ]
 }
 
 @test "list: Image and its copy" {
@@ -92,9 +91,7 @@ teardown() {
   assert_line --index 1 --partial "$default_image"
   assert_line --index 2 --partial "$default_image-copy"
   assert [ ${#lines[@]} -eq 4 ]
-  if check_bats_version 1.7.0; then
-    assert [ ${#stderr_lines[@]} -eq 0 ]
-  fi
+  assert [ ${#stderr_lines[@]} -eq 0 ]
 }
 
 @test "list: Containers and images" {
@@ -114,9 +111,7 @@ teardown() {
   assert_line --index 1 --partial "fedora-toolbox:34"
   assert_line --index 2 --partial "$(get_system_id)-toolbox:$(get_system_version)"
   assert [ ${#lines[@]} -eq 4 ]
-  if check_bats_version 1.7.0; then
-    assert [ ${#stderr_lines[@]} -eq 0 ]
-  fi
+  assert [ ${#stderr_lines[@]} -eq 0 ]
 
   # Check containers
   run --keep-empty-lines --separate-stderr $TOOLBOX list --containers
@@ -126,9 +121,7 @@ teardown() {
   assert_line --index 2 --partial "non-default-one"
   assert_line --index 3 --partial "non-default-two"
   assert [ ${#lines[@]} -eq 5 ]
-  if check_bats_version 1.7.0; then
-    assert [ ${#stderr_lines[@]} -eq 0 ]
-  fi
+  assert [ ${#stderr_lines[@]} -eq 0 ]
 
   # Check all together
   run --keep-empty-lines --separate-stderr $TOOLBOX list
@@ -140,9 +133,7 @@ teardown() {
   assert_line --index 6 --partial "non-default-one"
   assert_line --index 7 --partial "non-default-two"
   assert [ ${#lines[@]} -eq 9 ]
-  if check_bats_version 1.7.0; then
-    assert [ ${#stderr_lines[@]} -eq 0 ]
-  fi
+  assert [ ${#stderr_lines[@]} -eq 0 ]
 }
 
 @test "list: Images with and without names" {
@@ -160,7 +151,5 @@ teardown() {
   assert_line --index 2 --partial "fedora-toolbox:34"
   assert_line --index 3 --partial "$default_image"
   assert [ ${#lines[@]} -eq 5 ]
-  if check_bats_version 1.7.0; then
-    assert [ ${#stderr_lines[@]} -eq 0 ]
-  fi
+  assert [ ${#stderr_lines[@]} -eq 0 ]
 }