Description of problem:
Bind9 server-stale-enable default is ignored.

Version-Release number of selected component (if applicable): bind-9.11.13-3.el8


How reproducible: always


I am using the following named.conf configuration:

```
# cat /etc/named.conf


options {
  listen-on port 53 { 127.0.0.1; };
  use-v4-udp-ports { range 9000 65535; };
  use-v6-udp-ports { range 9000 65535; };

  directory       "/var/named";
  dump-file       "/var/named/data/cache_dump.db";
  statistics-file "/var/named/data/named_stats.txt";
  memstatistics-file "/var/named/data/named_mem_stats.txt";
  secroots-file   "/var/named/data/named.secroots";
  recursing-file  "/var/named/data/named.recursing";

  allow-query     { localhost; };
  allow-query-cache { localhost; };

  // Only forward and cache requests
  forward only;
  forwarders { 8.8.4.4; 8.8.8.8; };

  // DNSsec
  dnssec-enable yes;
  dnssec-validation yes;
  managed-keys-directory "/var/named/dynamic";

  max-cache-ttl 3600;
  max-ncache-ttl 3600;

  pid-file "/run/named/named.pid";
  session-keyfile "/run/named/session.key";

};

view localhost_resolver {
  match-clients      { localhost; };
  match-destinations { localhost; };
  recursion yes;
  include "/etc/named.rfc1912.zones";
};

logging {
  channel default_debug {
    print-time yes;
    print-category yes;
    print-severity yes;
    file "data/named.run";
    severity dynamic;
  };
};
```

and `serve-stale-enable` is not enabled, neither in config nor via rncd.

```
# rndc serve-stale status 

localhost_resolver: off (stale-answer-ttl=1 max-stale-ttl=604800)
_bind: off (stale-answer-ttl=1 max-stale-ttl=604800)
```

However a cache dump of this running server gives the following output:

```
# cat /var/named/data/cache_dump.db 
;
; Start view localhost_resolver
;
;
; Cache dump of view 'localhost_resolver' (cache localhost_resolver)
;
; using a 604800 second stale ttl
$DATE 20200515091102
; answer
access.redhat.com.	608272	IN CNAME access.redhat.com.edgekey.net.
; answer
downloads.redhat.com.	608360	CNAME	downloads.redhat.com.edgekey.net.
; answer
e133.b.akamaiedge.net.	604756	A	104.96.151.22
; answer
e1890.dscd.akamaiedge.net. 604780 A	172.227.162.153
; answer
access.redhat.com.edgekey.net. 608337 CNAME e133.b.akamaiedge.net.
; answer
downloads.redhat.com.edgekey.net. 608361 CNAME e1890.dscd.akamaiedge.net.
```

According to the Bind9 documentation, `server-stable-enable`  should be off by default.
Quoting here the relevant part of bind-9.11-serve-stale.patch

```
+             <listitem>
+               <para>
+                 Enable the returning of stale answers when the
+                 nameservers for the zone are not answering.  This
+                 is off by default but can be enabled/disabled via
+                 <command>rndc server-stale on</command> and
+                 <command>rndc server-stale off</command> which
+                 override the named.conf setting.  <command>rndc
+                 server-stale reset</command> will restore control
+                 via named.conf.
+               </para>
+             </listitem>
```

If I am not missing something, it looks like the default is not respected, since bind9 tracks the server-stale TTLs for each record in the cache dump.
Expected here was a decreasing max-cache-ttl, going from 3600 to 0 as it was in older bind9 releases (9.11.4-9.P2.el7 for instance)