Revert "blocks: add double single quote block recognition (#78)" (#89)

This reverts commit 1e5a257.

`''` is also how many languages express an empty string, which shouldn't
be treated as a quote. #78 causes quite a few problems for many files
internally, and I assume it'd also cause problems externally.

Author: JeffFaer

goldens/block.in

@@ -155,19 +155,3 @@ some_build_rule(
     src = "one-more-source",
 )
 // keep-sorted-test end
-
-// Nix multi line string
-// keep-sorted-test start block=yes newline_separated=yes
-foo = throw ''
-  Some text here.
-
-  Text has empty lines.
-'';
-
-bar = ''
-  While foo throws, this is just a string
-
-
-    Again, with some spaces here and there.
-'';
-// keep-sorted-test end

goldens/block.out

@@ -157,19 +157,3 @@ some_build_rule(
     src = "another-source",
 )
 // keep-sorted-test end
-
-// Nix multi line string
-// keep-sorted-test start block=yes newline_separated=yes
-bar = ''
-  While foo throws, this is just a string
-
-
-    Again, with some spaces here and there.
-'';
-
-foo = throw ''
-  Some text here.
-
-  Text has empty lines.
-'';
-// keep-sorted-test end

keepsorted/line_group.go

@@ -251,7 +251,7 @@ var (
 	}
 	quotes = []string{
 		`"""`, `'''`, "```",
-		`"`, `''`, `'`, "`",
+		`"`, `'`, "`",
 	}
 )