Simplify/fix loop descriptions in regex source generator (#118341)

- There's no need to say "greedily and atomically"... "atomically" covers it.
- "lazily and atomically" doesn't make sense... "lazily" covers it.

Author: stephentoub

src/libraries/System.Text.RegularExpressions/gen/RegexGenerator.Emitter.cs

@@ -5813,9 +5813,8 @@ private static string DescribeLoop(RegexNode node, RegexMethod rm)
                 _ when node.M == node.N => "exactly",
                 RegexNodeKind.Oneloopatomic or RegexNodeKind.Notoneloopatomic or RegexNodeKind.Setloopatomic => "atomically",
                 RegexNodeKind.Oneloop or RegexNodeKind.Notoneloop or RegexNodeKind.Setloop => "greedily",
-                RegexNodeKind.Onelazy or RegexNodeKind.Notonelazy or RegexNodeKind.Setlazy => "lazily",
-                RegexNodeKind.Loop => rm.Analysis.IsAtomicByAncestor(node) ? "greedily and atomically" : "greedily",
-                _ /* RegexNodeKind.Lazyloop */ => rm.Analysis.IsAtomicByAncestor(node) ? "lazily and atomically" : "lazily",
+                RegexNodeKind.Loop => rm.Analysis.IsAtomicByAncestor(node) ? "atomically" : "greedily",
+                _ => "lazily", // Onelazy or Notonelazy or Setlazy or Lazyloop
             };
 
             string bounds =