fix(mdns): Remove strict mode as it's invalid

Strict mode was introduced to support "one-shot" queries (described in
RFC6762/sec5.1) that are sent by lwip or dig. It was incorrectly assumed
that responding to such queries violates the spec, as we have to repeat
queries in responces, which is forbidden in RFC6762/sec6. It is however
required to repeat query fields according to the Section 6.7. Legacy
Unicast Responses: "it MUST repeat the query ID and the question
given in the query message."

components/mdns/Kconfig

@@ -64,17 +64,6 @@ menu "mDNS"
             Configures timeout for adding a new mDNS service. Adding a service
             fails if could not be completed within this time.
 
-    config MDNS_STRICT_MODE
-        bool "mDNS strict mode"
-        default "n"
-        help
-            Configures strict mode. Set this to 1 for the mDNS library to strictly follow the RFC6762:
-            Currently the only strict feature: Do not repeat original questions in response packets
-            (defined in RFC6762 sec. 6).
-            Default configuration is 0, i.e. non-strict mode, since some implementations,
-            such as lwIP mDNS resolver (used by standard POSIX API like getaddrinfo, gethostbyname)
-            could not correctly resolve advertised names.
-
     config MDNS_TIMER_PERIOD_MS
         int "mDNS timer period (ms)"
         range 10 10000