Revert "Make selection more consistent across languages (#17084)" (#17175)

This reverts commit 7db8d80c30.(#17084)

Release Notes:

- N/A

crates/languages/src/markdown/config.toml

@@ -1,6 +1,7 @@
 name = "Markdown"
 grammar = "markdown"
 path_suffixes = ["md", "mdx", "mdwn", "markdown"]
+word_characters = ["-"]
 brackets = [
     { start = "{", end = "}", close = true, newline = true },
     { start = "[", end = "]", close = true, newline = true },