repo: Bump lock timeout to 5 minutes

And update the doc text to talk about having a timeout at all
by default being a mistake.

Timeouts are really best handled at a higher level; if two processes
are contending for the ostree lock and one is actually frozen,
resolving this is something an admin may want to handle and introspect/debug
instead of having the waiter error out.

Most people using ostree are doing it in a way in which they have
higher level timeouts (e.g. on a container pod).

man/ostree.repo-config.xml

@@ -229,7 +229,10 @@ License along with this library. If not, see <https://www.gnu.org/licenses/>.
         <term><varname>lock-timeout-secs</varname></term>
         <listitem><para>Integer value controlling the number of seconds to
         block while attempting to acquire a lock (see above). A value
-        of -1 means block indefinitely. The default value is 30.
+        of -1 means block indefinitely. The default value is 300.  This timeout
+        is now regarded as a mistake; because it's likely to cause flakes.
+        It's recommended to set it to -1, and have timeouts at a higher application
+        level if desired.
         </para></listitem>
       </varlistentry>
 

src/libostree/ostree-repo.c

@@ -3081,7 +3081,7 @@ reload_core_config (OstreeRepo *self, GCancellable *cancellable, GError **error)
       {
         g_autofree char *lock_timeout_seconds = NULL;
 
-        if (!ot_keyfile_get_value_with_default (self->config, "core", "lock-timeout-secs", "30",
+        if (!ot_keyfile_get_value_with_default (self->config, "core", "lock-timeout-secs", "300",
                                                 &lock_timeout_seconds, error))
           return FALSE;