fix: line breaks in multiline strings, issue 13157 (#13274)

Co-authored-by: Georgii Dolzhykov <thorn.mailbox@gmail.com>
Co-authored-by: Gleb Dolzhikov <gleb.dolzhikov@ix.co>
Co-authored-by: fisker Cheung <lionkay@gmail.com>

changelog_unreleased/javascript/13274.md

@@ -0,0 +1,34 @@
+#### Fix inconsistent formatting for multiline strings (#13274 by @GlebDolzhikov)
+
+<!-- prettier-ignore -->
+```jsx
+// Input
+const loremIpsumFooBazBar1 = 'Multiline string\
+         Multiline string\
+'
+
+const loremIpsumFooBazBar2 = 'Multiline string\
+         Multiline string\
+         Multiline string'
+
+// Prettier stable
+const loremIpsumFooBazBar1 = "Multiline string\
+         Multiline string\
+";
+
+const loremIpsumFooBazBar2 =
+  "Multiline string\
+         Multiline string\
+         Multiline string";
+
+// Prettier main
+const loremIpsumFooBazBar1 =
+  "Multiline string\
+         Multiline string\
+";
+
+const loremIpsumFooBazBar2 =
+  "Multiline string\
+         Multiline string\
+         Multiline string";
+```