Pull request: 4904 return dhcp msg size

Merge in DNS/adguard-home from 4904-rm-padding to master

Updates #4904.
Updates #4903.

Squashed commit of the following:

commit 85337402ad64395704028534f17ac1887cff64e8
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Fri Sep 9 19:38:09 2022 +0300

    dhcpd: return dhcp msg size

CHANGELOG.md

@@ -15,12 +15,18 @@ and this project adheres to
 ## [v0.108.0] - 2022-12-01 (APPROX.)
 -->
 
+### Changed
+
+- The minimum DHCP message size is reassigned back to BOOTP's constraint of 300
+  bytes ([#4904]).
+
 ### Security
 
 - Weaker cipher suites that use the CBC (cipher block chaining) mode of
   operation have been disabled ([#2993]).
 
 [#2993]: https://github.com/AdguardTeam/AdGuardHome/issues/2993
+[#4904]: https://github.com/AdguardTeam/AdGuardHome/issues/4904