MINOR: log/balance: rename "log-sticky" to "sticky"

After giving it some thought, it could pretty well happen that other
protocols benefit from the sticky algorithm that some used to emulate
using a "stick-on int(0)" or things like this previously. So better
rename it to "sticky" right now instead of having to keep that "log-"
prefix forever. It's still limited to logs, of course, only the algo
is renamed in the config.

doc/configuration.txt

@@ -4932,12 +4932,13 @@ balance url_param <param> [check_post]
                   This algorithm is only usable for backends in LOG mode, for
                   others, please use "hash" instead.
 
-      log-sticky  Tries to stick to the same server as much as possible. The
+      sticky      Tries to stick to the same server as much as possible. The
                   first server in the list of available servers receives all
                   the log messages. When the server goes DOWN, the next server
                   in the list takes its place. When a previously DOWN server
                   goes back UP it is added at the end of the list so that the
-                  sticky server doesn't change until it becomes DOWN.
+                  sticky server doesn't change until it becomes DOWN. This
+                  algorithm is only usable for backends in LOG mode.
 
     <arguments> is an optional list of arguments which may be needed by some
                 algorithms. Right now, only "url_param", "uri" and "log-hash"

reg-tests/log/log_backend.vtc

@@ -79,7 +79,7 @@ haproxy h1 -conf {
 
         backend mylog-failover
                 mode log
-		balance log-sticky
+                balance sticky
 
                 server s1 udp@${Slg21_addr}:${Slg21_port}        # only receives "GET /srv1" request
                 server s2 udp@${Slg22_addr}:${Slg22_port}        # only receives "GET /srv2" request

src/backend.c

@@ -2834,12 +2834,12 @@ int backend_parse_balance(const char **args, char **err, struct proxy *curproxy)
 		ha_free(&curproxy->lbprm.arg_str);
 		curproxy->lbprm.arg_str = strdup(args[1]);
 	}
-	else if (strcmp(args[0], "log-sticky") == 0) {
+	else if (strcmp(args[0], "sticky") == 0) {
 		curproxy->lbprm.algo &= ~BE_LB_ALGO;
 		curproxy->lbprm.algo |= BE_LB_ALGO_LS;
 	}
 	else {
-		memprintf(err, "only supports 'roundrobin', 'static-rr', 'leastconn', 'source', 'uri', 'url_param', 'hash', 'hdr(name)', 'rdp-cookie(name)', 'log-hash' and 'log-sticky' options.");
+		memprintf(err, "only supports 'roundrobin', 'static-rr', 'leastconn', 'source', 'uri', 'url_param', 'hash', 'hdr(name)', 'rdp-cookie(name)', 'log-hash' and 'sticky' options.");
 		return -1;
 	}
 	return 0;