[5.1.x] Removed "Expected" from release date for 5.1.9 and 4.2.21.

Backport of c861563 from main.

Author: nessita

docs/releases/4.2.21.txt

@@ -2,7 +2,7 @@
 Django 4.2.21 release notes
 ===========================
 
-*Expected May 7, 2025*
+*May 7, 2025*
 
 Django 4.2.21 fixes a security issue with severity "moderate", a data loss bug,
 and a regression in 4.2.20.

docs/releases/5.1.9.txt

@@ -2,7 +2,7 @@
 Django 5.1.9 release notes
 ==========================
 
-*Expected May 7, 2025*
+*May 7, 2025*
 
 Django 5.1.9 fixes a security issue with severity "moderate", a data loss bug,
 and a regression in 5.1.8.