some test cleanups & category reorganization (#22010)

* clean up some test categories

* mention exact slice issue

* magics into system

* move trangechecks into overflow

* move tmemory to system

* try fix CI

* try fix CI

* final CI fix

tests/array/tinvalidarrayaccess.nim

@@ -0,0 +1,21 @@
+discard """
+  errormsg: "index 2 not in 0 .. 1"
+  line: 18
+"""
+block:
+  try:
+    let a = @[1,2]
+    echo a[3]
+  except Exception as e:
+    doAssert e.msg == "index 3 not in 0 .. 1"
+      # note: this is not being tested, because the CT error happens before
+
+block:
+  type TTestArr = array[0..1, int16]
+  var f: TTestArr
+  f[0] = 30
+  f[1] = 40
+  f[2] = 50
+  f[3] = 60
+
+  echo(repr(f))